Internet
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This article is
about the public worldwide computer network system. For other uses, see Internet (disambiguation).
Routing
paths through a portion of the Internet as visualized by the Opte
Project
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General
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Internet
Society (ISOC)
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Domain Name System (DNS)
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Hypertext Transfer Protocol (HTTP)
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Internet Protocol (IP)
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Internet Protocol Suite (TCP/IP)
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Services
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Blogs ·
Microblogs ·
E-mail
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Shopping ·
Voice
over IP (VoIP)
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Guides
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This
box:
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Computer
network types by geographical scope
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The Internet
is a global system of interconnected computer
networks that use the standard Internet protocol suite (often called
TCP/IP, although not all applications use TCP) to serve billions of users
worldwide. It is a network of networks that consists of millions of
private, public, academic, business, and government networks, of local to
global scope, that are linked by a broad array of electronic, wireless and
optical networking technologies. The Internet carries an extensive range of
information resources and services, such as the inter-linked hypertext
documents of the World Wide Web (WWW) and the infrastructure to support email.
Most
traditional communications media including telephone, music, film, and
television are reshaped or redefined by the Internet, giving birth to new
services such as Voice over Internet Protocol (VoIP)
and Internet Protocol Television (IPTV).
Newspaper, book and other print publishing are adapting to Web site
technology, or are reshaped into blogging and web feeds. The Internet has enabled and accelerated new
forms of human interactions through instant messaging, Internet forums, and
social networking. Online
shopping has boomed both for major retail outlets and small artisans and
traders. Business-to-business and financial services on the Internet
affect supply
chains across entire industries.
The origins of
the Internet reach back to research of the 1960s, commissioned by the United States government in collaboration
with private commercial interests to build robust, fault-tolerant, and
distributed computer networks. The funding of a new U.S. backbone by the National Science Foundation in the
1980s, as well as private funding for other commercial backbones, led to
worldwide participation in the development of new networking technologies, and
the merger of many networks. The commercialization
of what was by the 1990s an international network resulted in its
popularization and incorporation into virtually every aspect of modern human
life. As of 2011
more than 2.2 billion people—nearly a third of Earth's
Human population—used the services of the Internet.[1]
The Internet
has no centralized governance in either technological implementation or
policies for access and usage; each constituent network sets its own standards.
Only the overreaching definitions of the two principal name spaces
in the Internet, the Internet Protocol address space and the Domain Name System, are directed by a
maintainer organization, the Internet
Corporation for Assigned Names and Numbers (ICANN). The technical
underpinning and standardization of the core protocols (IPv4 and IPv6) is an activity of
the Internet Engineering Task Force
(IETF), a non-profit organization of loosely affiliated international participants
that anyone may associate with by contributing technical expertise.
Contents
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Terminology
See also: Internet capitalization conventions
Internet is a short
form of the technical term internetwork,[2] the
result of interconnecting computer networks with special gateways or routers.
Historically the word has been used, uncapitalized, as a verb and adjective
since 1883 to refer to interconnected motions. It was also used from 1974
before the Internet, uncapitalized, as a verb meaning to connect
together, especially for networks.[3] The
Internet is also often referred to as the Net.
The Internet,
referring to the specific entire global system of IP networks, is a proper noun
and written with an initial capital
letter. In the media and common use it is often not capitalized: "the
internet". Some guides specify that the word should be capitalized as a
noun but not capitalized as an adjective.[4]
The terms Internet
and World Wide Web are often used interchangeably in everyday speech; it
is common to speak of going on the Internet when invoking a browser
to view Web pages. However, the Internet is a particular global computer
network connecting millions of computing devices; the World
Wide Web is just one of many services running on the Internet. The
Web is a collection of interconnected documents (Web pages)
and other resources, linked by hyperlinks
and URLs.[5] In
addition to the Web, a multitude of other services are implemented over the
Internet, including e-mail,
file transfer, remote computer control, newsgroups,
and online
games. Web (and other) services can be implemented on any intranet,
accessible to network users.
History
Professor Leonard
Kleinrock with the first ARPANET Interface Message Processors at UCLA
Main articles: History of the Internet and History of the World Wide Web
Research into packet
switching started in the early 1960s and packet switched networks such as
Mark I at NPL in the UK,[6]
ARPANET, CYCLADES,[7][8] Merit
Network,[9]
Tymnet, and Telenet, were
developed in the late 1960s and early 1970s using a variety of protocols. The ARPANET in particular led to
the development of protocols for internetworking,
where multiple separate networks could be joined together into a network of
networks thanks to the work of British
scientist Donald Davies whose ground-breaking work on Packet
Switching was essential to the system.[10]
The first two
nodes of what would become the ARPANET were interconnected between Leonard Kleinrock's Network Measurement
Center at the UCLA's School
of Engineering and Applied Science and Douglas Engelbart's NLS system at SRI International (SRI) in Menlo Park, California, on 29
October 1969.[11]
The third site on the ARPANET was the Culler-Fried Interactive Mathematics
center at the University of California at
Santa Barbara, and the fourth was the University of Utah Graphics
Department. In an early sign of future growth, there were already fifteen sites
connected to the young ARPANET by the end of 1971.[12][13] These
early years were documented in the 1972 film Computer Networks:
The Heralds of Resource Sharing.
Early
international collaborations on ARPANET were sparse. For various political
reasons, European developers were concerned with developing the X.25 networks.[14]
Notable exceptions were the Norwegian Seismic Array (NORSAR) in 1972,
followed in 1973 by Sweden with satellite links to the Tanum Earth Station and Peter T. Kirstein's research group in
the UK, initially at the Institute of Computer Science, London
University and later at University College London.[15]
T3 NSFNET
Backbone, c. 1992
In December
1974, RFC 675 –
Specification of Internet Transmission Control Program, by Vinton Cerf,
Yogen Dalal, and Carl Sunshine, used the term internet, as a shorthand
for internetworking; later RFCs repeat this use, so the word started out
as an adjective
rather than the noun
it is today.[16]
Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF)
developed the Computer
Science Network (CSNET). In 1982, the Internet Protocol Suite (TCP/IP) was
standardized and the concept of a world-wide network of fully interconnected
TCP/IP networks called the Internet was introduced.
TCP/IP network
access expanded again in 1986 when the National Science Foundation Network (NSFNET) provided
access to supercomputer sites in the United States from research
and education organizations, first at 56 kbit/s and later at 1.5 Mbit/s and 45
Mbit/s.[17]
Commercial internet service providers (ISPs) began
to emerge in the late 1980s and early 1990s. The ARPANET was decommissioned in
1990. The Internet was commercialized in 1995 when NSFNET was decommissioned,
removing the last restrictions on the use of the Internet to carry commercial
traffic.[18]
The Internet started a rapid expansion to Europe and Australia in the mid to
late 1980s[19][20] and to
Asia in the late 1980s and early 1990s.[21]
This NeXT
Computer was used by Sir Tim Berners-Lee at CERN and became the
world's first Web server.
Since the
mid-1990s the Internet has had a tremendous impact on culture and commerce,
including the rise of near instant communication by email, instant
messaging, Voice over Internet Protocol (VoIP)
"phone calls", two-way interactive video calls, and the World
Wide Web[22]
with its discussion forums, blogs, social
networking, and online shopping sites. Increasing amounts
of data are transmitted at higher and higher speeds over fiber optic networks
operating at 1-Gbit/s, 10-Gbit/s, or more. The Internet continues to grow,
driven by ever greater amounts of online information and knowledge, commerce,
entertainment and social networking.[23]
During the late
1990s, it was estimated that traffic on the public Internet grew by 100 percent
per year, while the mean annual growth in the number of Internet users was
thought to be between 20% and 50%.[24] This
growth is often attributed to the lack of central administration, which allows
organic growth of the network, as well as the non-proprietary open nature of
the Internet protocols, which encourages vendor interoperability and prevents
any one company from exerting too much control over the network.[25] As of
31 March 2011, the estimated total number of Internet
users was 2.095 billion (30.2% of world population).[26]
It is estimated that in 1993 the Internet carried only 1% of the information
flowing through two-way telecommunication, by 2000 this figure had grown to
51%, and by 2007 more than 97% of all telecommunicated information was carried
over the Internet.[27]
Technology
Protocols
Main article: Internet protocol suite
As the user
data is processed down through the protocol stack, each layer adds an
encapsulation at the sending host. Data is transmitted "over the
wire" at the link level, left to right. The encapsulation stack procedure
is reversed by the receiving host. Intermediate relays remove and add a new
link encapsulation for retransmission, and inspect the IP layer for routing
purposes.
*
Not a layer. A routing protocol belongs either to application or network
layer.
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The
communications infrastructure of the Internet consists of its hardware
components and a system of software layers that control various aspects of the
architecture. While the hardware can often be used to support other software
systems, it is the design and the rigorous standardization process of the
software architecture that characterizes the Internet and provides the
foundation for its scalability and success. The responsibility for the
architectural design of the Internet software systems has been delegated to the
Internet Engineering Task Force
(IETF).[28]
The IETF conducts standard-setting work groups, open to any individual, about
the various aspects of Internet architecture. Resulting discussions and final
standards are published in a series of publications, each called a Request for Comments (RFC), freely
available on the IETF web site. The principal methods of networking that enable
the Internet are contained in specially designated RFCs that constitute the Internet Standards. Other less rigorous
documents are simply informative, experimental, or historical, or document the
best current practices (BCP) when implementing Internet technologies.
The Internet
standards describe a framework known as the Internet protocol suite. This is a model
architecture that divides methods into a layered system of protocols (RFC 1122, RFC 1123). The layers correspond
to the environment or scope in which their services operate. At the top is the application layer, the space for the
application-specific networking methods used in software applications, e.g., a
web browser program. Below this top layer, the transport
layer connects applications on different hosts via the network
(e.g., client–server model) with appropriate data
exchange methods. Underlying these layers are the core networking technologies,
consisting of two layers. The internet
layer enables computers to identify and locate each other via Internet
Protocol (IP) addresses, and allows them to connect to one another via
intermediate (transit) networks. Last, at the bottom of the architecture, is a
software layer, the link layer, that provides connectivity between hosts on
the same local network link, such as a local area network (LAN) or a dial-up connection. The model, also known
as TCP/IP, is
designed to be independent of the underlying hardware, which the model
therefore does not concern itself with in any detail. Other models have been
developed, such as the Open Systems Interconnection (OSI)
model, but they are not compatible in the details of description or
implementation; many similarities exist and the TCP/IP protocols are usually
included in the discussion of OSI networking.
The most
prominent component of the Internet model is the Internet Protocol (IP), which
provides addressing systems (IP addresses) for computers on the Internet. IP enables
internetworking and in essence establishes the Internet itself. IP Version 4 (IPv4) is the initial
version used on the first generation of today's Internet and is still in
dominant use. It was designed to address up to ~4.3 billion (109)
Internet hosts. However, the explosive growth of the Internet has led to IPv4 address exhaustion, which entered its
final stage in 2011,[29] when
the global address allocation pool was exhausted. A new protocol version, IPv6,
was developed in the mid-1990s, which provides vastly larger addressing
capabilities and more efficient routing of Internet traffic. IPv6 is currently in
growing deployment around the world, since
Internet address registries (RIRs) began to urge all resource
managers to plan rapid adoption and conversion.[30]
IPv6 is not
interoperable with IPv4. In essence, it establishes a parallel version of the
Internet not directly accessible with IPv4 software. This means software
upgrades or translator facilities are necessary for networking devices that
need to communicate on both networks. Most modern computer operating systems
already support both versions of the Internet Protocol. Network
infrastructures, however, are still lagging in this development. Aside from the
complex array of physical connections that make up its infrastructure, the
Internet is facilitated by bi- or multi-lateral commercial contracts (e.g., peering agreements), and by technical
specifications or protocols that describe how to exchange data over the
network. Indeed, the Internet is defined by its interconnections and routing
policies.
Routing
Internet packet
routing is accomplished among various tiers of Internet Service Providers.
Internet Service Providers connect
customers (thought of at the "bottom" of the routing hierarchy) to
customers of other ISPs. At the "top" of the routing hierarchy are
ten or so Tier 1 networks, large telecommunication
companies which exchange traffic directly "across" to all other Tier
1 networks via unpaid peering agreements. Tier
2 networks buy Internet transit from other ISP to reach
at least some parties on the global Internet, though they may also engage in
unpaid peering (especially for local partners of a similar size). ISPs can use
a single "upstream" provider for connectivity, or use multihoming
to provide protection from problems with individual links. Internet exchange points create physical
connections between multiple ISPs, often hosted in buildings owned by
independent third parties.[citation needed]
Computers and
routers use routing tables to direct IP packets among locally
connected machines. Tables can be constructed manually or automatically via DHCP for an individual
computer or a routing protocol for routers themselves.
In single-homed situations, a default
route usually points "up" toward an ISP providing transit.
Higher-level ISPs use the Border Gateway Protocol to sort out paths
to any given range of IP addresses across the
complex connections of the global Internet.[citation needed]
Academic
institutions, large companies, governments, and other organizations can perform
the same role as ISPs, engaging in peering and purchasing transit on behalf of
their internal networks of individual computers. Research networks tend to
interconnect into large subnetworks such as GEANT, GLORIAD, Internet2,
and the UK's national research and education
network, JANET.
These in turn are built around smaller networks (see the list of academic computer
network organizations).[citation needed]
Not all computer
networks are connected to the Internet. For example, some classified United States websites
are only accessible from separate secure networks.[citation needed]
General structure
The Internet
structure and its usage characteristics have been studied extensively. It has
been determined that both the Internet IP routing structure and hypertext links
of the World Wide Web are examples of scale-free networks.[31]
Many computer
scientists describe the Internet as a "prime example of a large-scale,
highly engineered, yet highly complex system".[32] The
Internet is heterogeneous; for instance, data transfer rates and physical
characteristics of connections vary widely. The Internet exhibits "emergent
phenomena" that depend on its large-scale organization. For example,
data transfer rates exhibit temporal self-similarity.
The principles of the routing and addressing methods for traffic in the
Internet reach back to their origins in the 1960s when the eventual scale and
popularity of the network could not be anticipated. Thus, the possibility of
developing alternative structures is investigated.[33] The
Internet structure was found to be highly robust[34] to
random failures and very vulnerable to high degree attacks.[35]
Governance
Main article: Internet governance
ICANN
headquarters in Marina Del Rey, California, United States
The Internet is
a globally
distributed network comprising many voluntarily interconnected autonomous
networks. It operates without a central governing body. However, to maintain
interoperability, all technical and policy aspects of the underlying core
infrastructure and the principal name spaces
are administered by the Internet
Corporation for Assigned Names and Numbers (ICANN), headquartered in Marina del Rey, California. ICANN is the
authority that coordinates the assignment of unique identifiers for use on the
Internet, including domain names, Internet Protocol (IP) addresses,
application port numbers in the transport protocols, and many other parameters.
Globally unified name spaces, in which names and numbers are uniquely assigned,
are essential for the global reach of the Internet. ICANN is governed by an
international board of directors drawn from across the Internet technical,
business, academic, and other non-commercial communities. The government of the
United States continues to have the primary role in approving changes to the DNS
root zone that lies at the heart of the domain name system.[36]
ICANN's role in coordinating the assignment of unique identifiers distinguishes
it as perhaps the only central coordinating body on the global Internet. On 16
November 2005, the World Summit on the Information
Society, held in Tunis,
established the Internet Governance Forum (IGF) to
discuss Internet-related issues.
Modern uses
The Internet
allows greater flexibility in working hours and location, especially with the
spread of unmetered high-speed connections. The Internet can be accessed almost
anywhere by numerous means, including through mobile Internet devices. Mobile
phones, datacards,
handheld game consoles and cellular
routers allow users to connect to the Internet wirelessly.
Within the limitations imposed by small screens and other limited facilities of
such pocket-sized devices, the services of the Internet, including email and
the web, may be available. Service providers may restrict the services offered
and mobile data charges may be significantly higher than other access methods.
Educational
material at all levels from pre-school to post-doctoral is available from
websites. Examples range from CBeebies, through school and high-school revision guides, virtual universities, to access to
top-end scholarly literature through the likes of Google
Scholar. For distance education, help with homework and
other assignments, self-guided learning, whiling away spare time, or just
looking up more detail on an interesting fact, it has never been easier for
people to access educational information at any level from anywhere. The
Internet in general and the World
Wide Web in particular are important enablers of both formal and informal education.
The low cost
and nearly instantaneous sharing of ideas, knowledge, and skills has made collaborative
work dramatically easier, with the help of collaborative software. Not only can a group
cheaply communicate and share ideas but the wide reach of the Internet allows
such groups more easily to form. An example of this is the free software movement, which has produced,
among other things, Linux,
Mozilla
Firefox, and OpenOffice.org. Internet chat, whether in the form of
an IRC chat room or
channel, via an instant messaging system, or a social networking website, allows
colleagues to stay in touch in a very convenient way when working at their
computers during the day. Messages can be exchanged even more quickly and
conveniently than via email. These systems may allow files to be exchanged,
drawings and images to be shared, or voice and video contact between team
members.
Content management systems allow collaborating
teams to work on shared sets of documents simultaneously without accidentally
destroying each other's work. Business and project teams can share calendars as
well as documents and other information. Such collaboration occurs in a wide
variety of areas including scientific research, software development,
conference planning, political activism and creative writing. Social and
political collaboration is also becoming more widespread as both Internet
access and computer literacy spread.
The Internet
allows computer users to remotely access other computers and information stores
easily, wherever they may be. They may do this with or without computer
security, i.e. authentication and encryption technologies, depending on the
requirements. This is encouraging new ways of working from home, collaboration
and information sharing in many industries. An accountant sitting at home can audit the books of a
company based in another country, on a server situated in a third country
that is remotely maintained by IT specialists in a fourth. These accounts could
have been created by home-working bookkeepers, in other remote locations, based
on information emailed to them from offices all over the world. Some of these
things were possible before the widespread use of the Internet, but the cost of
private leased
lines would have made many of them infeasible in practice. An office worker
away from their desk, perhaps on the other side of the world on a business trip
or a holiday, can access their emails, access their data using cloud
computing, or open a remote desktop session into their office PC
using a secure Virtual Private Network (VPN) connection on
the Internet. This can give the worker complete access to all of their normal
files and data, including email and other applications, while away from the
office. This concept has been referred to among system administrators as the Virtual
Private Nightmare,[37]
because it extends the secure perimeter of a corporate network into remote
locations and its employees' homes.
Services
World Wide Web
Many people use
the terms Internet and World Wide Web, or just the Web,
interchangeably, but the two terms are not synonymous.
The World Wide Web is a global set of documents, images and other resources, logically
interrelated by hyperlinks and referenced with Uniform Resource Identifiers (URIs).
URIs symbolically identify services, servers,
and other databases, and the documents and resources that they can provide. Hypertext Transfer Protocol (HTTP) is
the main access protocol of the World Wide Web, but it is only one of the
hundreds of communication protocols used on the Internet. Web
services also use HTTP to allow software systems to communicate in order to
share and exchange business logic and data.
World Wide Web
browser software, such as Microsoft's Internet Explorer, Mozilla
Firefox, Opera, Apple's Safari, and Google
Chrome, lets users navigate from one web page to another via hyperlinks
embedded in the documents. These documents may also contain any combination of computer
data, including graphics, sounds, text, video, multimedia
and interactive content that runs while the user is interacting with the page. Client-side software can include animations, games,
office applications and scientific
demonstrations. Through keyword-driven Internet
research using search engines like Yahoo!
and Google, users worldwide have easy, instant
access to a vast and diverse amount of online information. Compared to printed
media, books, encyclopedias and traditional libraries, the World Wide Web has
enabled the decentralization of information on a large scale.
The Web has
also enabled individuals and organizations to publish ideas and
information to a potentially large audience online
at greatly reduced expense and time delay. Publishing a web page, a blog, or
building a website involves little initial cost and many cost-free
services are available. Publishing and maintaining large, professional web
sites with attractive, diverse and up-to-date information is still a difficult
and expensive proposition, however. Many individuals and some companies and
groups use web logs or blogs, which are largely used as easily updatable
online diaries. Some commercial organizations encourage staff to
communicate advice in their areas of specialization in the hope that visitors
will be impressed by the expert knowledge and free information, and be
attracted to the corporation as a result. One example of this practice is Microsoft,
whose product developers publish their personal blogs
in order to pique the public's interest in their work. Collections of personal
web pages published by large service providers remain popular, and have become
increasingly sophisticated. Whereas operations such as Angelfire and
GeoCities
have existed since the early days of the Web, newer offerings from, for
example, Facebook and Twitter currently have large followings. These operations
often brand themselves as social network services rather
than simply as web page hosts.
Advertising on popular web pages can be
lucrative, and e-commerce or the sale of products and services directly
via the Web continues to grow.
When the Web
began in the 1990s, a typical web page was stored in completed form on a web
server, formatted in HTML,
ready to be sent to a user's browser in response to a request. Over time, the
process of creating and serving web pages has become more automated and more
dynamic. Websites are often created using content management or wiki software with,
initially, very little content. Contributors to these systems, who may be paid
staff, members of a club or other organization or members of the public, fill
underlying databases with content using editing pages designed for that
purpose, while casual visitors view and read this content in its final HTML
form. There may or may not be editorial, approval and security systems built
into the process of taking newly entered content and making it available to the
target visitors.
Communication
Email is an
important communications service available on the Internet. The concept of
sending electronic text messages between parties in a way analogous to mailing
letters or memos predates the creation of the Internet. Pictures, documents and
other files are sent as email attachments. Emails can be cc-ed
to multiple email addresses.
Internet telephony is another common
communications service made possible by the creation of the Internet. VoIP stands for
Voice-over-Internet Protocol, referring to the
protocol that underlies all Internet communication. The idea began in the early
1990s with walkie-talkie-like voice applications for personal
computers. In recent years many VoIP systems have become as easy to use and as
convenient as a normal telephone. The benefit is that, as the Internet carries
the voice traffic, VoIP can be free or cost much less than a traditional
telephone call, especially over long distances and especially for those with
always-on Internet connections such as cable
or ADSL. VoIP is
maturing into a competitive alternative to traditional telephone service.
Interoperability between different providers has improved and the ability to
call or receive a call from a traditional telephone is available. Simple,
inexpensive VoIP network adapters are available that eliminate the need for a
personal computer.
Voice quality
can still vary from call to call, but is often equal to and can even exceed
that of traditional calls. Remaining problems for VoIP include emergency telephone number dialing and
reliability. Currently, a few VoIP providers provide an emergency service, but
it is not universally available. Traditional phones are line-powered and
operate during a power failure; VoIP does not do so without a backup power source for the phone
equipment and the Internet access devices. VoIP has also become increasingly
popular for gaming applications, as a form of communication between players.
Popular VoIP clients for gaming include Ventrilo and Teamspeak. Wii, PlayStation
3, and Xbox
360 also offer VoIP chat features.
Data transfer
File
sharing is an example of transferring large amounts of data across the Internet.
A computer
file can be emailed to customers, colleagues and friends as an attachment.
It can be uploaded to a website or FTP server for easy download by
others. It can be put into a "shared location" or onto a file server
for instant use by colleagues. The load of bulk downloads to many users can be
eased by the use of "mirror" servers or peer-to-peer
networks. In any of these cases, access to the file may be controlled by user authentication,
the transit of the file over the Internet may be obscured by encryption,
and money may change hands for access to the file. The price can be paid by the
remote charging of funds from, for example, a credit card whose details are
also passed – usually fully encrypted – across the Internet. The origin and
authenticity of the file received may be checked by digital
signatures or by MD5
or other message digests. These simple features of the Internet, over a
worldwide basis, are changing the production, sale, and distribution of
anything that can be reduced to a computer file for transmission. This includes
all manner of print publications, software products, news, music, film, video,
photography, graphics and the other arts. This in turn has caused seismic
shifts in each of the existing industries that previously controlled the
production and distribution of these products.
Streaming
media is the real-time delivery of digital media for the immediate
consumption or enjoyment by end users. Many radio and television broadcasters
provide Internet feeds of their live audio and video productions. They may also
allow time-shift viewing or listening such as Preview, Classic Clips and Listen
Again features. These providers have been joined by a range of pure Internet
"broadcasters" who never had on-air licenses. This means that an
Internet-connected device, such as a computer or something more specific, can
be used to access on-line media in much the same way as was previously possible
only with a television or radio receiver. The range of available types of
content is much wider, from specialized technical webcasts to
on-demand popular multimedia services. Podcasting is a
variation on this theme, where – usually audio – material is downloaded and
played back on a computer or shifted to a portable media player to be listened to on the
move. These techniques using simple equipment allow anybody, with little
censorship or licensing control, to broadcast audio-visual material worldwide.
Digital media
streaming increases the demand for network bandwidth. For example, standard
image quality needs 1 Mbit/s link speed for SD 480p, HD 720p quality requires
2.5 Mbit/s, and the top-of-the-line HDX quality needs 4.5 Mbit/s for 1080p.[38]
Webcams are a
low-cost extension of this phenomenon. While some webcams can give
full-frame-rate video, the picture either is usually small or updates slowly.
Internet users can watch animals around an African waterhole, ships in the Panama
Canal, traffic at a local roundabout or monitor their own premises, live
and in real time. Video chat rooms and video conferencing are also popular
with many uses being found for personal webcams, with and without two-way
sound. YouTube was founded on 15 February 2005 and is now the leading website
for free streaming video with a vast number of users. It uses a flash-based
web player to stream and show video files. Registered users may upload an
unlimited amount of video and build their own personal profile. YouTube claims
that its users watch hundreds of millions, and upload hundreds of thousands of
videos daily.[39]
Access
Main article: Internet
access
Common methods
of Internet access in homes include dial-up,
landline broadband (over coaxial
cable, fiber optic or copper wires), Wi-Fi, satellite and 3G/4G technology cell
phones. Public places to use the Internet include libraries and Internet
cafes, where computers with Internet connections are available. There are
also Internet access points in many public
places such as airport halls and coffee shops, in some cases just for brief use
while standing. Various terms are used, such as "public Internet
kiosk", "public access terminal", and "Web payphone".
Many hotels now also have public terminals, though these are usually fee-based.
These terminals are widely accessed for various usage like ticket booking, bank
deposit, online payment etc. Wi-Fi provides wireless access to computer
networks, and therefore can do so to the Internet itself. Hotspots providing such access include Wi-Fi
cafes, where would-be users need to bring their own wireless-enabled
devices such as a laptop or PDA. These services may be free to all,
free to customers only, or fee-based. A hotspot need not be limited to a
confined location. A whole campus or park, or even an entire city can be
enabled.
Grassroots
efforts have led to wireless community networks. Commercial
Wi-Fi services covering large city areas are in place in London, Vienna, Toronto, San
Francisco, Philadelphia, Chicago and Pittsburgh.
The Internet can then be accessed from such places as a park bench.[40] Apart
from Wi-Fi, there have been experiments with proprietary mobile wireless
networks like Ricochet, various high-speed data
services over cellular phone networks, and fixed wireless services. High-end
mobile phones such as smartphones in general come with Internet access through
the phone network. Web browsers such as Opera are available on these advanced
handsets, which can also run a wide variety of other Internet software. More
mobile phones have Internet access than PCs, though this is not as widely used.[41] An
Internet access provider and protocol matrix differentiates the methods used to
get online.
An Internet
blackout or outage can be caused by local signaling interruptions. Disruptions of
submarine communications cables may
cause blackouts or slowdowns to large areas, such as in the 2008 submarine cable disruption.
Less-developed countries are more vulnerable due to a small number of
high-capacity links. Land cables are also vulnerable, as in 2011 when a woman
digging for scrap metal severed most connectivity for the nation of Armenia.[42]
Internet blackouts affecting almost entire countries can be achieved by
governments as a form of Internet censorship, as in the
blockage of the Internet in Egypt, whereby
approximately 93%[43]
of networks were without access in 2011 in an attempt to stop mobilization for anti-government protests.[44]
Users
See also: Global Internet usage, English on the Internet, and Unicode
Overall
Internet usage has seen tremendous growth. From 2000 to 2009, the number of
Internet users globally rose from 394 million to 1.858 billion.[48] By
2010, 22 percent of the world's population had access to computers with 1
billion Google
searches every day, 300 million Internet users reading blogs, and 2 billion
videos viewed daily on YouTube.[49]
The prevalent
language for communication on the Internet has been English. This may be a
result of the origin of the Internet, as well as the language's role as a lingua
franca. Early computer systems were limited to the characters in the American Standard Code
for Information Interchange (ASCII), a subset of the Latin
alphabet.
After English
(27%), the most requested languages on the World
Wide Web are Chinese (23%), Spanish (8%), Japanese (5%), Portuguese and
German (4% each), Arabic, French and Russian (3% each), and Korean (2%).[50] By
region, 42% of the world's Internet users are based in Asia, 24% in
Europe, 14% in North America, 10% in Latin America and the Caribbean
taken together, 6% in Africa, 3% in the Middle East and 1% in
Australia/Oceania.[51]
The Internet's technologies have developed enough in recent years, especially
in the use of Unicode,
that good facilities are available for development and communication in the
world's widely used languages. However, some glitches such as mojibake
(incorrect display of some languages' characters) still remain.
In an American
study in 2005, the percentage of men using the Internet was very slightly ahead
of the percentage of women, although this difference reversed in those under
30. Men logged on more often, spent more time online, and were more likely to
be broadband users, whereas women tended to make more use of opportunities to
communicate (such as email). Men were more likely to use the Internet to pay
bills, participate in auctions, and for recreation such as downloading music
and videos. Men and women were equally likely to use the Internet for shopping
and banking.[52]
More recent studies indicate that in 2008, women significantly outnumbered men
on most social networking sites, such as Facebook and Myspace, although the
ratios varied with age.[53] In
addition, women watched more streaming content, whereas men downloaded more.[54] In
terms of blogs, men were more likely to blog in the first place; among those
who blog, men were more likely to have a professional blog, whereas women were
more likely to have a personal blog.[55]
Social impact
Main article: Sociology of the Internet
The Internet
has enabled entirely new forms of social interaction, activities, and
organizing, thanks to its basic features such as widespread usability and
access. In the first decade of the 21st century, the first generation is raised
with widespread availability of Internet connectivity, bringing consequences
and concerns in areas such as personal privacy and identity, and distribution
of copyrighted materials. These "digital
natives" face a variety of challenges that were not present for prior
generations.
Social networking and entertainment
See also: Social networking service#Social impact
Many people use
the World Wide Web to access news, weather and sports reports, to plan and book
vacations and to find out more about their interests. People use chat,
messaging and email to make and stay in touch with friends worldwide, sometimes
in the same way as some previously had pen pals.
The Internet has seen a growing number of Web
desktops, where users can access their files and settings via the Internet.
Social networking websites such as Facebook, Twitter, and MySpace have
created new ways to socialize and interact. Users of these sites are able to
add a wide variety of information to pages, to pursue common interests, and to
connect with others. It is also possible to find existing acquaintances, to
allow communication among existing groups of people. Sites like LinkedIn foster
commercial and business connections. YouTube and Flickr specialize
in users' videos and photographs.
The Internet
has been a major outlet for leisure activity since its inception, with
entertaining social experiments such as MUDs and MOOs being conducted on
university servers, and humor-related Usenet groups
receiving much traffic. Today, many Internet
forums have sections devoted to games and funny videos; short cartoons in
the form of Flash movies are also popular. Over
6 million people use blogs or message boards as a means of communication and
for the sharing of ideas. The pornography and gambling industries have taken
advantage of the World Wide Web, and often provide a significant source of
advertising revenue for other websites.[56]
Although many governments have attempted to restrict both industries' use of
the Internet, in general this has failed to stop their widespread popularity.[57]
Another area of
leisure activity on the Internet is multiplayer gaming.[58] This
form of recreation creates communities, where people of all ages and origins
enjoy the fast-paced world of multiplayer games. These range from MMORPG to first-person shooters, from role-playing video games to online
gambling. While online gaming has been around since the 1970s, modern modes
of online gaming began with subscription services such as GameSpy
and MPlayer.[59]
Non-subscribers were limited to certain types of game play or certain games.
Many people use the Internet to access and download music, movies and other
works for their enjoyment and relaxation. Free and fee-based services exist for
all of these activities, using centralized servers and distributed peer-to-peer
technologies. Some of these sources exercise more care with respect to the
original artists' copyrights than others.
Internet usage
has been correlated to users' loneliness.[60] Lonely
people tend to use the Internet as an outlet for their feelings and to share
their stories with others, such as in the "I am lonely will anyone speak to me"
thread.
Cybersectarianism
is a new organizational form which involves: "highly dispersed small
groups of practitioners that may remain largely anonymous within the larger
social context and operate in relative secrecy, while still linked remotely to
a larger network of believers who share a set of practices and texts, and often
a common devotion to a particular leader. Overseas supporters provide funding
and support; domestic practitioners distribute tracts, participate in acts of
resistance, and share information on the internal situation with outsiders.
Collectively, members and practitioners of such sects construct viable virtual
communities of faith, exchanging personal testimonies and engaging in
collective study via email, on-line chat rooms and web-based message
boards."[61]
Cyberslacking
can become a drain on corporate resources; the average UK employee spent 57
minutes a day surfing the Web while at work, according to a 2003 study by
Peninsula Business Services.[62] Internet addiction disorder is
excessive computer use that interferes with daily life. Psychologist Nicolas
Carr believe that Internet use has other effects on individuals, for
instance improving skills of scan-reading and interfering with the deep
thinking that leads to true creativity.[63]
Politics and political revolutions
The Internet
has achieved new relevance as a political tool. The presidential campaign of Howard Dean
in 2004 in the United States was notable for its success in soliciting donation
via the Internet. Many political groups use the Internet to achieve a new
method of organizing in order to carry out their mission, having given rise to Internet activism, most notably
practiced by rebels in the Arab Spring.[64][65]
The New
York Times suggested that social
media websites such as Facebook and Twitter helped people organize the
political revolutions in Egypt where it helped certain classes of protesters
organize protests, communicate grievances, and disseminate information.[66]
The potential
of the Internet as a civic tool of communicative power was thoroughly explored
by Simon R. B. Berdal in his
thesis of 2004:
As the globally
evolving Internet provides ever new access points to virtual discourse forums,
it also promotes new civic relations and associations within which
communicative power may flow and accumulate. Thus, traditionally ...
national-embedded peripheries get entangled into greater, international
peripheries, with stronger combined powers... The Internet, as a consequence,
changes the topology of the "centre-periphery" model, by stimulating
conventional peripheries to interlink into "super-periphery"
structures, which enclose and "besiege" several centres at once.[67]
Berdal,
therefore, extends the Habermasian notion of the Public
sphere to the Internet, and underlines the inherent global and civic nature
that intervowen Internet technologies provide. To limit the growing civic
potential of the Internet, Berdal also notes how "self-protective
measures" are put in place by those threatened by it:
If we consider
China’s attempts to filter "unsuitable material" from the Internet,
most of us would agree that this resembles a self-protective measure by the
system against the growing civic potentials of the Internet. Nevertheless, both
types represent limitations to "peripheral capacities". Thus, the
Chinese government tries to prevent communicative power to build up and unleash
(as the 1989 Tiananmen Square uprising
suggests, the government may find it wise to install "upstream
measures"). Even though limited, the Internet is proving to be an
empowering tool also to the Chinese periphery: Analysts believe that Internet
petitions have influenced policy implementation in favour of the public’s
online-articulated will ...[67]
Philanthropy
The spread of
low-cost internet access in developing countries has opened up new
possibilities for peer-to-peer charities, which allow
individuals to contribute small amounts to charitable projects for other
individuals. Websites such as DonorsChoose
and GlobalGiving
allow small-scale donors to direct funds to individual projects of their
choice.
A popular twist
on internet-based philanthropy is the use of peer-to-peer lending for charitable purposes. Kiva pioneered this
concept in 2005, offering the first web-based service to publish individual
loan profiles for funding. Kiva raises funds for local intermediary microfinance
organizations which post stories and updates on behalf of the borrowers.
Lenders can contribute as little as $25 to loans of their choice, and receive
their money back as borrowers repay. Kiva falls short of being a pure
peer-to-peer charity, in that loans are disbursed before being funded by
lenders and borrowers do not communicate with lenders themselves.[68][69]
However, the
recent spread of low cost Internet access in developing countries has made genuine international
person-to-person philanthropy increasingly feasible. In 2009 the US-based
nonprofit Zidisha
tapped into this trend to offer the first person-to-person microfinance
platform to link lenders and borrowers across international borders without
intermediaries. Members can fund loans for as little as a dollar, which the
borrowers then use to develop business activities that improve their families'
incomes while repaying loans to the members with interest. Borrowers access the
internet via public cybercafes, donated laptops in village schools, and even
smart phones, then create their own profile pages through which they share
photos and information about themselves and their businesses. As they repay
their loans, borrowers continue to share updates and dialogue with lenders via
their profile pages. This direct web-based connection allows members themselves
to take on many of the communication and recording tasks traditionally
performed by local organizations, bypassing geographic barriers and
dramatically reducing the cost of microfinance services to the entrepreneurs.[70]
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