Wikipedia originally developed from another encyclopedia project called Nupedia.
The volumes of the 15th edition of Encyclopædia Britannica (and the volume for the year 2002) span two bookshelves in a library.
The Internet Messenger by Buky Schwartz, located in Holon, Israel
Wikipedia's desktop homepage
Title page of Lucubrationes, 1541 edition, one of the first books to use a variant of the word encyclopedia in the title
T3 NSFNET Backbone, c. 1992.
The Wikipedia home page on December 20, 2001
Naturalis Historiæ, 1669 edition, title page
ICANN headquarters in the Playa Vista neighborhood of Los Angeles, California, United States.
Cartogram showing number of articles in each European language One square represents 10,000 articles. Languages with fewer than 10,000 articles are represented by one square. Languages are grouped by language family and each language family is presented by a separate color.
Isidore of Seville author of Etymologiae (10th. century Ottonian manuscript)
2007 map showing submarine fiberoptic telecommunication cables around the world.
Screenshot of English Wikipedia's article on Earth, 30 March 2021
The Yongle Encyclopedia
Packet routing across the Internet involves several tiers of Internet service providers.
Differences between versions of an article are highlighted
Number of mobile cellular subscriptions 2012–2016
Wikipedia's editing interface
As user data is processed through the protocol stack, each abstraction layer adds encapsulation information at the sending host. Data is transmitted over the wire at the link level between hosts and routers. Encapsulation is removed by the receiving host. Intermediate relays update link encapsulation at each hop, and inspect the IP layer for routing purposes.
American journalist John Seigenthaler (1927–2014), subject of the Seigenthaler incident.
Conceptual data flow in a simple network topology of two hosts (A and B) connected by a link between their respective routers. The application on each host executes read and write operations as if the processes were directly connected to each other by some kind of data pipe. After the establishment of this pipe, most details of the communication are hidden from each process, as the underlying principles of communication are implemented in the lower protocol layers. In analogy, at the transport layer the communication appears as host-to-host, without knowledge of the application data structures and the connecting routers, while at the internetworking layer, individual network boundaries are traversed at each router.
Most popular edition of Wikipedia by country in January 2021.
A DNS resolver consults three name servers to resolve the domain name user-visible "" to determine the IPV4 Address
Most viewed editions of Wikipedia over time.
Creating a subnet by dividing the host identifier
Most edited editions of Wikipedia over time.
This NeXT Computer was used by Tim Berners-Lee at CERN and became the world's first Web server.
A graph for pageviews of Turkish Wikipedia shows a large drop of roughly 80% immediately after the block of Wikipedia in Turkey was imposed in 2017.
Share of population using the Internet. See or edit source data.
Estimation of contributions shares from different regions in the world to different Wikipedia editions
Internet users per 100 population members and GDP per capita for selected countries.
Number of editors on the English Wikipedia over time.
Internet users per 100 inhabitants Source: International Telecommunication Union.
Pie chart of Wikipedia content by subject
Internet users in 2015 as a percentage of a country's population Source: International Telecommunication Union.
Katherine Maher became the third executive director of Wikimedia in 2016, succeeding Lila Tretikov, who had taken over from Sue Gardner in 2014.
'''Fixed broadband Internet subscriptions in 2012
as a percentage of a country's population''' Source: International Telecommunication Union.
Overview of system architecture
'''Mobile broadband Internet subscriptions in 2012
as a percentage of a country's population''' Source: International Telecommunication Union.
The mobile version of the English Wikipedia's main page, from August 3, 2019
Banner in Bangkok during the 2014 Thai coup d'état, informing the Thai public that 'like' or 'share' activities on social media could result in imprisonment (observed 30 June 2014).
Wikipedia Monument in Słubice, Poland (2014, by Mihran Hakobyan)
Internet users by language<ref name=NIUBL-IWS>{{cite web|url=|title=Number of Internet Users by Language|archive-url=|archive-date=26 April 2012|website=Internet World Stats, Miniwatts Marketing Group|date=31 May 2011|access-date=22 April 2012}}</ref>
Jimmy Wales accepts the 2008 Quadriga A Mission of Enlightenment award on behalf of Wikipedia
Website content languages<ref name=UofCLBWApril2013>{{cite web|title=Usage of content languages for websites|url=||access-date=26 April 2013|archive-url=|archive-date=31 March 2012|url-status=live}}</ref>
Wikipedia team visiting the Parliament of Asturias
Wikipedians meeting after the 2015 Asturias awards ceremony
A group of Wikimedians of the Wikimedia DC chapter at the 2013 DC Wikimedia annual meeting standing in front of the Encyclopædia Britannica (back left) at the US National Archives

Wikipedia ( or ) is a multilingual free online encyclopedia written and maintained by a community of volunteers through open collaboration and a wiki-based editing system.

- Wikipedia

Global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices.

- Internet

The appearance of digital and open-source versions in the 21st century, such as Wikipedia, has vastly expanded the accessibility, authorship, readership, and variety of encyclopedia entries.

- Encyclopedia

500 related topics



Reference to data that the user can follow by clicking or tapping.

An example of a hyperlink as commonly seen in a web browser, with a mouse pointer hovering above it
Several documents being connected by hyperlinks
How internal MediaWiki links work when one wants to create a link that displays words different from the linked page's title.
Douglas Engelbart and his team at SRI, 1969

For example, in an online reference work such as Wikipedia, or Google, many words and terms in the text are hyperlinked to definitions of those terms.

Tim Berners-Lee saw the possibility of using hyperlinks to link any information to any other information over the Internet.

Reference work

Work, such as a book or periodical , to which one can refer for information.

The Brockhaus Enzyklopädie, the best-known traditional reference book in German-speaking countries
The Lexikon des Mittelalters, a specialised German encyclopedia
Encyclopædia Britannica, 15th edition: volumes of the Propedia (green), Micropedia (red), Macropedia (black), and 2-volume Index (blue)

Reference works include encyclopedias, almanacs, atlases, bibliographies, biographical sources, catalogs such as library catalogs and art catalogs, concordances, dictionaries, directories such as business directories and telephone directories, discographies, filmographies, gazetteers, glossaries, handbooks, indices such as bibliographic indices and citation indices, manuals, research guides, thesauruses, and yearbooks.

Many reference works are available in electronic form and can be obtained as reference software, CD-ROMs, DVDs, or online through the Internet.

Wikipedia, an online encyclopedia, is both the largest and the most-read reference work in history.


Process of two or more people, entities or organizations working together to complete a task or achieve a goal.

Catalan castellers collaborate, working together with a shared goal.
Organization and cooperation between community members provides economic and social benefits.
The 2,751 Liberty ships built in four years by the United States during World War II required new approaches in organization and manufacturing.
The Evergreen signature clock tower
Trilateral agreement between ESO, the National Science Foundation and the National Institutes of Natural Sciences for the operation of ALMA

Websites and software facilitate musical collaboration over the Internet, resulting in the emergence of online bands.

Examples of products created by means of commons-based peer production include Linux, a computer operating system; Slashdot, a news and announcements website; Kuro5hin, a discussion site for technology and culture; Wikipedia, an online encyclopedia; and Clickworkers, a collaborative scientific work.

World Wide Web

World's dominant software platform.

The historic World Wide Web logo, designed by Robert Cailliau.
A web page displayed in a web browser
A global map of the Web Index for countries in 2014
This NeXT Computer was used by Sir Tim Berners-Lee at CERN and became the world's first Web server.
The World Wide Web functions as an application layer protocol that is run "on top of" (figuratively) the Internet, helping to make it more functional. The advent of the Mosaic web browser helped to make the web much more usable, to include the display of images and moving images (GIFs).
Graphic representation of a minute fraction of the WWW, demonstrating hyperlinks
A screenshot of a web page on Wikimedia Commons
Dynamic web page: example of server-side scripting (PHP and MySQL)
The website
The inside and front of a Dell PowerEdge web server, a computer designed for rack mounting
Multiple web servers may be used for a high traffic website; here, Dell servers are installed together to be used for the Wikimedia Foundation.
The results of a search for the term "lunar eclipse" in a web-based image search engine

It is an information space where documents and other web resources can be accessed through the Internet using a web browser.

Notable examples are,, and


Hypertext publication collaboratively edited and managed by its own audience directly.

Editing display showing MediaWiki markup language
Ward Cunningham
Wiki Wiki Shuttle at Honolulu International Airport
History comparison reports highlight the changes between two revisions of a page.
The home page of the English Wikipedia

The online encyclopedia project, Wikipedia, is the most popular wiki-based website, and is one of the most widely viewed sites in the world, having been ranked in the top twenty since 2007.

All that people require to contribute is a computer, Internet access, a web browser, and a basic understanding of a simple markup language (e.g. MediaWiki markup language).

Internet access

Internet Connectivity Access layer
Satellite Internet access via VSAT in Ghana
Service mark for GSMA
Wi-Fi logo
Wi-Fi range diagram
Broadband affordability in 2011 This map presents an overview of broadband affordability, as the relationship between average yearly income per capita and the cost of a broadband subscription (data referring to 2011). Source: Information Geographies at the Oxford Internet Institute.
Internet users in 2015 as a percentage of a country's population Source: International Telecommunication Union.
'''Fixed broadband Internet subscriptions in 2012
as a percentage of a country's population''' Source: International Telecommunication Union.
'''Mobile broadband Internet subscriptions in 2012
as a percentage of a country's population''' Source: International Telecommunication Union.
The digital divide measured in terms of bandwidth is not closing, but fluctuating up and down. Gini coefficients for telecommunication capacity (in kbit/s) among individuals worldwide

Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web.

Internet services like Facebook, Wikipedia and Google have built special programs to partner with mobile network operators (MNO) to introduce zero-rating the cost for their data volumes as a means to provide their service more broadly into developing markets.

Social media

Social media are interactive digital channels that facilitate the creation and sharing of information, ideas, interests, and other forms of expression through virtual communities and networks.

Social media app icons on a smartphone
SixDegrees, launched in 1997, is often regarded as the first social media site.

1) Social media are interactive Web 2.0 Internet-based applications.

Collaborative projects (ex. Wikipedia, Mozilla)

Mobile web

The mobile web refers to mobile browser-based World Wide Web services accessed from handheld mobile devices, such as smartphones or feature phones, through a mobile or other wireless network.

Websites re-designed for mobile screens, with sizes ranging from smartphones, netbooks, and tablets, to laptops, with a desktop screen shown for scale
Wikipedia viewed with Opera Mini mobile web browser on a small-screen cellphone.
Evolution of mobile web standards
Total data consumed by Opera Mini users worldwide from 2006 to mid-2008 in TB
Social network service mobile graphical user interface (Facebook)

Web designers may work separately on such pages, or pages may be automatically converted, as in Mobile Wikipedia.

Mobile Internet refers to Internet access and mainly usage of Internet using a cellular telephone service provider or mobile wireless network.


Standard markup language for documents designed to be displayed in a web browser.

Tim Berners-Lee in April 2009
Logo of HTML5

In 1989, Berners-Lee wrote a memo proposing an Internet-based hypertext system.

In his personal notes from 1990 he listed "some of the many areas in which hypertext is used" and put an encyclopedia first.


Worldwide distributed discussion system available on computers.

A diagram of Usenet servers and clients. The blue, green, and red dots on the servers represent the groups they carry. Arrows between servers indicate newsgroup group exchanges (feeds). Arrows between clients and servers indicate that a user is subscribed to a certain group and reads or submits articles.
Usenet Provider Map
The "Big Nine" hierarchies of Usenet
A visual example of the many complex steps required to prepare data to be uploaded to Usenet newsgroups. These steps must be done again in reverse to download data from Usenet.
October 2020 screenshot showing 60 PB of usenet group data.

In the early 1990s, shortly before access to the Internet became commonly affordable, Usenet connections via Fidonet's dial-up BBS networks made long-distance or worldwide discussions and other communication widespread, not needing a server, just (local) telephone service.