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Wiki
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This article is about the type of website. For other uses, see Wiki (disambiguation).
File:Ward Cunningham, Inventor of the Wiki.webm
Interview with Ward Cunningham, inventor of the wiki
A wiki (/?w?ki/ (About this soundlisten) WIK-ee) is a hypertext publication collaboratively edited and managed by its own audience directly using a web browser. A typical wiki contains multiple pages for the subjects or scope of the project and may be either open to the public or limited to use within an organization for maintaining its internal knowledge base.

Wikis are enabled by wiki software, otherwise known as wiki engines. A wiki engine, being a form of a content management system, differs from other web-based systems such as blog software, in that the content is created without any defined owner or leader, and wikis have little inherent structure, allowing structure to emerge according to the needs of the users.[1] Wiki engines usually allow content to be written using a simplified markup language and sometimes edited with the help of a rich-text editor.[2] There are dozens of different wiki engines in use, both standalone and part of other software, such as bug tracking systems. Some wiki engines are open source, whereas others are proprietary. Some permit control over different functions (levels of access); for example, editing rights may permit changing, adding, or removing material. Others may permit access without enforcing access control. Other rules may be imposed to organize content.

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 ten since 2007.[3] Wikipedia is not a single wiki but rather a collection of hundreds of wikis, with each one pertaining to a specific language. In addition to Wikipedia, there are hundreds of thousands of other wikis in use, both public and private, including wikis functioning as knowledge management resources, notetaking tools, community websites, and intranets. The English-language Wikipedia has the largest collection of articles: as of February 2020, it has over 6 million articles. Ward Cunningham, the developer of the first wiki software, WikiWikiWeb, originally described wiki as "the simplest online database that could possibly work."[4] "Wiki" (pronounced [?wiki][note 1]) is a Hawaiian word meaning "quick."[5][6][7]


Contents
1 Characteristics
1.1 Editing
1.1.1 Navigation
1.1.2 Consistency
1.1.3 Basic syntax
1.1.4 Visual editing
1.1.5 Version history
1.1.6 Edit summary
1.2 Navigation
1.3 Linking and creating pages
1.4 Searching
2 History
3 Alternative definitions
4 Implementations
5 Trust and security
5.1 Controlling changes
5.2 Trustworthiness and reliability of content
5.3 Security
5.3.1 Potential malware vector
6 Communities
6.1 Applications
6.2 City wikis
6.3 WikiNodes
6.4 Participants
6.5 Growth factors
7 Conferences
8 Rules
9 Legal environment
10 See also
11 Notes
12 References
13 Further reading
14 External links
Characteristics

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Ward Cunningham, inventor of the wiki
Ward Cunningham and co-author Bo Leuf, in their book The Wiki Way: Quick Collaboration on the Web, described the essence of the Wiki concept as follows:[8]

A wiki invites all users—not just experts—to edit any page or to create new pages within the wiki Web site, using only a standard "plain-vanilla" Web browser without any extra add-ons.
Wiki promotes meaningful topic associations between different pages by making page link creation intuitively easy and showing whether an intended target page exists or not.
A wiki is not a carefully crafted site created by experts and professional writers, and designed for casual visitors. Instead, it seeks to involve the typical visitor/user in an ongoing process of creation and collaboration that constantly changes the website landscape.
A wiki enables communities of editors and contributors to write documents collaboratively. 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). A single page in a wiki website is referred to as a "wiki page", while the entire collection of pages, which are usually well-interconnected by hyperlinks, is "the wiki". A wiki is essentially a database for creating, browsing, and searching through information. A wiki allows non-linear, evolving, complex, and networked text, while also allowing for editor argument, debate, and interaction regarding the content and formatting.[9] A defining characteristic of wiki technology is the ease with which pages can be created and updated. Generally, there is no review by a moderator or gatekeeper before modifications are accepted and thus lead to changes on the website. Many wikis are open to alteration by the general public without requiring registration of user accounts. Many edits can be made in real-time and appear almost instantly online, but this feature facilitates abuse of the system. Private wiki servers require user authentication to edit pages, and sometimes even to read them. Maged N. Kamel Boulos, Cito Maramba, and Steve Wheeler write that the open wikis produce a process of Social Darwinism. "... because of the openness and rapidity that wiki pages can be edited, the pages undergo an evolutionary selection process not unlike that which nature subjects to living organisms. 'Unfit' sentences and sections are ruthlessly culled, edited and replaced if they are not considered 'fit', which hopefully results in the evolution of a higher quality and more relevant page."[10]

Editing
For the project page on editing Wikitext on Wikipedia, see Help:Wikitext.
Wikitext
Cheatsheet
All Wikitext
Magic links
Visual files
Sound files
Tables
Using templates
Using HTML codes within Wikitext
vte
Navigation
Some wikis have an Edit button or link directly on the page being viewed, if the user has permission to edit the page. This can lead to a text-based editing page where participants can structure and format wiki pages with a simplified markup language, sometimes known as Wikitext, Wiki markup or Wikicode (it can also lead to a WYSIWYG editing page; see the paragraph after the table below). For example, starting lines of text with asterisks could create a bulleted list. The style and syntax of wikitexts can vary greatly among wiki implementations,[example needed] some of which also allow HTML tags.

Consistency
Wikis have favoured plain-text editing, with fewer and simpler conventions than HTML, for indicating style and structure. Although limiting access to HTML and Cascading Style Sheets (CSS) of wikis limits user ability to alter the structure and formatting of wiki content, there are some benefits. Limited access to CSS promotes consistency in the look and feel, and having JavaScript disabled prevents a user from implementing code that may limit other users' access.

Basic syntax
MediaWiki syntax (the "behind the scenes" code used to add formatting to text) Equivalent HTML (another type of "behind the scenes" code used to add formatting to text) Rendered output (seen onscreen by a regular web user)
"Take some more [[tea]]," the March Hare said to Alice, very earnestly.

"I've had '''nothing''' yet," Alice replied in an offended tone, "so I can't take more."

"You mean you can't take ''less''," said the Hatter. "It's very easy to take ''more'' than nothing."
<p>"Take some more <a href="/wiki/Tea" title="Tea">tea</a>," the March Hare said to Alice, very earnestly.</p>

<p>"I've had <b>nothing</b> yet," Alice replied in an offended tone, "so I can't take more."</p>

<p>"You mean you can't take <i>less</i>," said the Hatter. "It's very easy to take <i>more</i> than nothing."</p>
"Take some more tea," the March Hare said to Alice, very earnestly.
"I've had nothing yet," Alice replied in an offended tone, "so I can't take more."

"You mean you can't take less," said the Hatter. "It's very easy to take more than nothing."


Visual editing
Wikis can also make WYSIWYG editing available to users, usually by means of JavaScript control that translates graphically entered formatting instructions into the corresponding HTML tags or wikitext. In those implementations, the markup of a newly edited, marked-up version of the page is generated and submitted to the server transparently, shielding the user from this technical detail. An example of this is the VisualEditor on Wikipedia. WYSIWYG controls do not, however, always provide all of the features available in wikitext, and some users prefer not to use a WYSIWYG editor. Hence, many of these sites offer some means to edit the wikitext directly.

Version history
Some wikis keep a record of changes made to wiki pages; often, every version of the page is stored. This means that authors can revert to an older version of the page should it be necessary because a mistake has been made, such as the content accidentally being deleted or the page has been vandalized to include offensive or malicious text or other inappropriate content.

Edit summary
Many wiki implementations, such as MediaWiki, the software that powers Wikipedia, allow users to supply an edit summary when they edit a page. This is a short piece of text summarizing the changes they have made (e.g., "Corrected grammar," or "Fixed formatting in table."). It is not inserted into the article's main text, but is stored along with that revision of the page, allowing users to explain what has been done and why, similar to a log message when making changes in a revision-control system. This enables other users to see which changes have been made by whom and why, often in a list of summaries, dates and other short, relevant content, a list which is called a "log" or "history."

Navigation
Within the text of most pages, there are usually many hypertext links to other pages within the wiki. This form of non-linear navigation is more "native" to a wiki than structured/formalized navigation schemes. Users can also create any number of index or table-of-contents pages, with hierarchical categorization or whatever form of organization they like. These may be challenging to maintain "by hand", as multiple authors and users may create and delete pages in an ad hoc, unorganized manner. Wikis can provide one or more ways to categorize or tag pages to support the maintenance of such index pages. Some wikis, including the original, have a backlink feature, which displays all pages that link to a given page. It is also typically possible in a wiki to create links to pages that do not yet exist, as a way to invite others to share what they know about a subject new to the wiki. Wiki users can typically "tag" pages with categories or keywords, to make it easier for other users to find the article. For example, a user creating a new article on cold weather cycling might "tag" this page under the categories of commuting, winter sports and bicycling. This would make it easier for other users to find the article.

Linking and creating pages
Links are created using a specific syntax, the so-called "link pattern". Originally, most wikis[citation needed] used CamelCase to name pages and create links. These are produced by capitalizing words in a phrase and removing the spaces between them (the word "CamelCase" is itself an example). While CamelCase makes linking easy, it also leads to links in a form that deviates from the standard spelling. To link to a page with a single-word title, one must abnormally capitalize one of the letters in the word (e.g. "WiKi" instead of "Wiki"). CamelCase-based wikis are instantly recognizable because they have many links with names such as "TableOfContents" and "BeginnerQuestions." It is possible for a wiki to render the visible anchor of such links "pretty" by reinserting spaces, and possibly also reverting to lower case. This reprocessing of the link to improve the readability of the anchor is, however, limited by the loss of capitalization information caused by CamelCase reversal. For example, "RichardWagner" should be rendered as "Richard Wagner", whereas "PopularMusic" should be rendered as "popular music". There is no easy way to determine which capital letters should remain capitalized. As a result, many wikis now have "free linking" using brackets, and some disable CamelCase by default.

Searching
Most wikis offer at least a title search, and sometimes a full-text search. The scalability of the search depends on whether the wiki engine uses a database. Some wikis, such as PmWiki, use flat files.[11] MediaWiki's first versions used flat files, but it was rewritten by Lee Daniel Crocker in the early 2000s (decade) to be a database application.[citation needed] Indexed database access is necessary for high speed searches on large wikis. Alternatively, external search engines such as Google Search can sometimes be used on wikis with limited searching functions in order to obtain more precise results.

History
Main article: History of wikis

Wiki Wiki Shuttle at Honolulu International Airport
WikiWikiWeb was the first wiki.[12] Ward Cunningham started developing WikiWikiWeb in Portland, Oregon, in 1994, and installed it on the Internet domain c2.com on March 25, 1995. It was named by Cunningham, who remembered a Honolulu International Airport counter employee telling him to take the "Wiki Wiki Shuttle" bus that runs between the airport's terminals. According to Cunningham, "I chose wiki-wiki as an alliterative substitute for 'quick' and thereby avoided naming this stuff quick-web."[13][14]

Cunningham was, in part, inspired by Apple Inc.'s HyperCard, which he had used. HyperCard, however, was single-user.[15] Apple had designed a system allowing users to create virtual "card stacks" supporting links among the various cards. Cunningham developed Vannevar Bush's ideas by allowing users to "comment on and change one another's text."[2][16] Cunningham says his goals were to link together people's experiences to create a new literature to document programming patterns, and to harness people's natural desire to talk and tell stories with a technology that would feel comfortable to those not used to "authoring".[15]

Wikipedia became the most famous wiki site, launched in January 2001 and entering the top ten most popular websites in 2007. In the early 2000s (decade), wikis were increasingly adopted in enterprise as collaborative software. Common uses included project communication, intranets, and documentation, initially for technical users. Some companies use wikis as their only collaborative software and as a replacement for static intranets, and some schools and universities use wikis to enhance group learning. There may be greater use of wikis behind firewalls than on the public Internet. On March 15, 2007, the word wiki was listed in the online Oxford English Dictionary.[17]

Alternative definitions
In the late 1990s and early 2000s, the word "wiki" was used to refer to both user-editable websites and the software that powers them; the latter definition is still occasionally in use.[1] Wiki inventor Ward Cunningham wrote in 2014[18] that the word "wiki" should not be used to refer to a single website, but rather to a mass of user-editable pages and or sites, so that a single website is not "a wiki" but "an instance of wiki". He wrote that the concept of wiki federation, in which the same content can be hosted and edited in more than one location in a manner similar to distributed version control, meant that the concept of a single discrete "wiki" no longer made sense.[19]

Implementations
See also: List of wiki software
Wiki software is a type of collaborative software that runs a wiki system, allowing web pages to be created and edited using a common web browser. It may be implemented as a series of scripts behind an existing web server, or as a standalone application server that runs on one or more web servers. The content is stored in a file system, and changes to the content are stored in a relational database management system. A commonly implemented software package is MediaWiki, which runs Wikipedia. Alternatively, personal wikis run as a standalone application on a single computer. WikidPad is an example. One application, TiddlyWiki, simply makes use of an even single local HTML file with JavaScript inside.

Wikis can also be created on a "wiki farm", where the server-side software is implemented by the wiki farm owner. PBwiki, Socialtext, and Wikia are popular examples of such services. Some wiki farms can also make private, password-protected wikis. Free wiki farms generally contain advertising on every page. For more information, see Comparison of wiki farms.

Trust and security
Controlling changes
"Recent changes" redirects here. For the Wikipedia help page, see Help:Recent changes. For the recent changes page itself, see Special:RecentChanges.

History comparison reports highlight the changes between two revisions of a page.
Wikis are generally designed with the philosophy of making it easy to correct mistakes, rather than making it difficult to make them. Thus, while wikis are very open, they provide a means to verify the validity of recent additions to the body of pages. The most prominent, on almost every wiki, is the "Recent Changes" page—a specific list numbering recent edits, or a list of edits made within a given time frame.[20] Some wikis can filter the list to remove minor edits and edits made by automatic importing scripts ("bots").[21] From the change log, other functions are accessible in most wikis: the revision history shows previous page versions and the diff feature highlights the changes between two revisions. Using the revision history, an editor can view and restore a previous version of the article. This gives great power to the author to eliminate edits. The diff feature can be used to decide whether or not this is necessary. A regular wiki user can view the diff of an edit list