The Wiki reference article from the English Wikipedia on 24-Jul-2004
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Wiki

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The terms wiki (pronounced "wicky" or "weeky") and WikiWiki are used to identify either a specific type of hypertext document collection or the collaborative software used to create it.

Wiki (with a capital 'W') and WikiWikiWeb are sometimes used to refer to the Portland Pattern Repository, the first ever wiki; proponents of this usage suggest using a lower-case 'w' to distinguish the generic terms discussed here. Wiki wiki comes from the Hawaiian term for "quick" or "super-fast".

Table of contents
1 Key characteristics
2 History
3 Wiki communities
4 Jargon
5 References
6 See also
7 External links

Key characteristics

A WikiWikiWeb enables documents to be written collectively in a simple markup language using a web browser. Because most wikis are web-based, the term "wiki" is usually sufficient. A single page in a wiki is referred to as a "wiki page", while the entire body of pages, which are usually highly interconnected, is called "the wiki".

One of the defining characteristics of wiki technology is the ease with which pages can be created and updated. Generally, there is no prior review before modifications are accepted, and most wikis are open to the general public - or at least anyone who has access to the wiki server. In fact, even registration of a user account is not always required.

Pages and editing

In traditional wikis, there are three representations for each page: the HTML code, the webpage resulting from rendering that code by a web browser, and the user-editable source code, from which the server produces the HTML. The latter format, known as "wikitext", is written in a simplified markup language whose style and syntax can vary among implementations.

The reasoning behind this design is that the HTML, with its large library of nested tags, is too complicated to allow fast-paced editing, and distracts from the actual content of the pages. It is also sometimes viewed as beneficial that users cannot use all the functionality that HTML allows, such as JavaScript and Cascading Style Sheets, because of the consistency in look and feel that is thereby enforced.

Wiki syntax (Wikipedia) HTML Rendered output
"''Doctor''? No other title? A ''scholar''? And he rates above the civil authority?"

"Why, certainly," replied Hardin, amiably. "We're all scholars more or less. After all, we're not so much a world as a scientific foundation – under the direct control of the Emperor."


"Doctor? No other title? A scholar? And he rates above the civil authority?"



"Why, certainly," replied Hardin, amiably. "We're all scholars more or less. After all, we're not so much a world as a scientific foundation – under the direct control of the Emperor."

"Doctor? No other title? A scholar? And he rates above the civil authority?"

"Why, certainly," replied Hardin, amiably. "We're all scholars more or less. After all, we're not so much a world as a scientific foundation – under the direct control of the Emperor."

(Quote from the book Foundation by Isaac Asimov)

Some recent wiki engines use a different method: they provide "WYSIWYG" editing, usually by means of an ActiveX control or plugin that translates graphically entered formatting instructions such as "bold" and "italics" into the corresponding HTML tags. In these implementations, saving an edit amounts to submitting a new HTML version of the page to the server, although the user is shielded from this technical detail as the markup is generated transparently. Users who do not have the necessary plugin can typically still edit the page, usually by directly editing the raw HTML code.

The formatting instructions allowed by a wiki vary considerably depending on the wiki engine that is used. Simple wikis only allow basic text formatting, whereas more complex ones have support for tables, images, formulas, or even interactive elements such as polls and games. Because of this, there is now an effort underway to define a Wiki Markup Standard.

Linking and creating pages

Wikis are a true hypertext medium, with non-linear navigational structures. Each page typically contains a large number of links to other pages. Hierarchical navigation pages often exist in larger wikis, but do not have to be used. Links are created using a specific syntax, the so-called "link pattern".

Originally, most wikis used CamelCase as a link pattern, produced by capitalizing words in a phrase and removing the spaces between them (the word "CamelCase" is itself an example of CamelCase). While CamelCase makes linking very easy, it also leads to links which are written in a form that deviates from the standard spelling. CamelCase-based wikis are instantly recognizable from the large number of links with names such as "TableOfContents" and "BeginnerQuestions".

CamelCase has many critics, and wiki developers looked for alternative solutions. The first to introduce so called "free links" using this _(free link format) was Cliki. Various wiki engines use single brackets, curly brackets, underscores, slashes or other characters as a link pattern. Links across different wiki communities are possible using a special link pattern called InterWiki.

New pages are usually created in a wiki simply by creating the appropriate links on a topically related page. If the link does not exist, it is typically emphasized as a "broken" link. Following that link opens an edit window, which then allows the user to enter the text for the new page. This mechanism ensures that so-called "orphan" pages (which have no links pointing to them) are rarely created, and a generally high level of connectedness is retained.

Wikis generally follow a philosophy of making it easy to fix mistakes instead of making it hard to make them. Thus, while wikis are very open, they also provide various means to verify the validity of recent additions to the body of pages. The most prominent one on almost every wiki is the so-called "Recent changes" page, which displays a list of either a specific number of recent edits or a list of all edits that have been made within a given timeframe. Some wikis allow the list to be filtered so that minor edits - or edits that have been made by automatic importing scripts ("bots") - can be excluded.

From the change log, two other functions are accessible in most wikis: the revision history, which shows previous versions of the page, and the diff feature, which can highlight the changes between two revisions. The revision history allows an editor to open and save a previous version of the page and thereby restore the original content. The diff feature can be used to decide whether this is necessary or not. A regular user of the wiki can view the diff of a change listed on the "Recent changes" page and, if it is an unacceptable edit, consult the history to restore a previous revision. This process is more or less streamlined, depending on the wiki software that is used.

Diff reports highlight the changes between two revisions of a pageEnlarge

Diff reports highlight the changes between two revisions of a page

In case unacceptable edits are missed on the "Recent changes" page, some wikis provide additional control over content. Tavi by Scott Moonen introduced "subscribed changes" (similar to Wikipedia's "watchlists"), a form of internal bookmarking that is used to generate a list of recent changes to a set of specific pages only. Wikipedia allows links to pages which are below a given size to be highlighted, thereby making small pages, so-called "stubs", noticeable on all pages that link to them.

In extreme cases, many wikis allow pages to be protected from editing. Protected pages on Wikipedia, for example, can only be edited by so-called administrators, who can also revoke the protection. This is generally considered to violate the basic philosophy of WikiWiki and is therefore usually avoided.

Controlling users

Most public wikis shun mandatory registration procedures. Nevertheless, many of the major wiki engines (including MediaWiki, MoinMoin, UseModWiki and TWiki) provide ways to limit write access. Some wiki engines allow individual users to be banned from editing, which can be accomplished by blocking their particular IP address or, if available, their username. However, many Internet service providers (ISPs) assign a new IP address for each login, so IP bans can often be circumvented relatively easily. To deal with this problem, temporary IP bans are sometimes used and extended to all IP addresses within a particular range, thereby ensuring that the vandal cannot edit pages within a given timeframe; the underlying assumption is that this is often sufficient as a deterrent. It may, however, also prevent some non-problem users from the same ISP using the service for the duration of the ban.

A common defence against a persistent "vandal" is to simply let them deface as many pages as they wish, knowing that they can easily be tracked and reverted after the vandal has left. This policy can quickly become impractical, however, in the face of systematic defacements born out of anger or frustration.

As an emergency measure, some wikis allow the database to be switched to read-only mode, while others enforce a policy in which only established users who have registered prior to some arbitrary cutoff date can continue editing. Generally speaking, however, any damage that is inflicted by a "vandal" can be reverted quickly and easily. More problematic are subtle errors inserted into pages which go undetected, for example changing of album release dates and discographies on Wikipedia.

Searching

Most wikis offer at least a title search, if not a full text search. The scalability of the search depends on whether the wiki engine uses a database or not; indexed database access is necessary for high speed searches on large wikis. On Wikipedia, the so-called "Go button" allows readers to directly view a page that matches the entered search criteria as closely as possible. The MetaWiki search engine was created to enable searches across multiple wikis.

Wiki engines

Given the relative simplicity of the wiki concept, a large number of implementations exist, ranging from very simple "hacks" implementing only core functionality to highly sophisticated content management systems. The majority of wiki engines are open source; large projects such as TWiki and the Wikipedia engine, MediaWiki, are developed collaboratively. Many wikis are highly modular, providing APIss which allow programmers to develop new features without requiring them to be familiar with the entire codebase.

It is hard to determine which wiki engines are the most popular, although a list of leading candidates might include UseMod, TWiki, MoinMoin and MediaWiki. See Wiki software for a list of wiki engines.

History

Wiki software originated in the design pattern community as a way of writing and discussing pattern languages. The Portland Pattern Repository was the first wiki, established by Ward Cunningham in 1995 [1]. Cunningham invented the wiki name and concept, and produced the first implementation of a wiki engine. Some people maintain that only the original wiki should be called Wiki (upper case) or the WikiWikiWeb. Ward's Wiki remains one of the most popular Wiki sites.

Cunningham named the term wiki for the "wiki wiki" or "quick" shuttle buses at Honolulu Airport. Wiki wiki was the first Hawaiian term he learned on his first visit to the islands, when the airport counter agent directed him to take the wiki wiki bus between terminals. According to Cunningham, "I chose wiki-wiki as an alliterative substitute for quick and thereby avoided naming this stuff quick-web." [1]. See also: List of computer term etymologies.

In the final years of the 20th century, wikis were increasingly recognized as a promising way to develop private and public knowledge bases, and it was this potential that inspired the founders of the Nupedia encyclopedia project, Jimbo Wales and Larry Sanger, to use wiki technology as a basis for an electronic encyclopedia: "Wikipedia" was launched in January 2001. It was originally based on the UseMod software, but later switched to its own open source codebase, which has now been adopted by many other wikis.

Today, the English Wikipedia is by far the world's largest wiki; the German language Wikipedia is the second largest, and the other non-English Wikipedias fill many of the other slots. The third largest wiki, however, is Susning.nu, a Swedish language knowledge base running the UseMod software. The all-encompassing nature of Wikipedia has been a significant factor in its growth, while many other wikis are highly specialized. Some have also attributed Wikipedia's rapid growth to its decision not to use CamelCase.

Wiki communities

All known public wiki are listed at WorldWideWiki: SwitchWiki, which currently lists about 1000 public wiki communities (as of 2004-06-12).

The 30 largest wiki are listed at Meatball: Biggest wikis .

One way of finding a wiki on some subject you are interested in is to follow the Wiki Node Network from wiki to wiki. Or you could take a Wiki bus tour: TourBusStop.

See list of wiki.

Jargon

Dozens of jargon terms have emerged in the wiki community.

WikiGnome

A friendly editor participating in a Wiki by contributing helpful little edits and additions without much noise. Obviously, this can be seen as a role adopted more or less occasionally by a person who may or may not be otherwise active on the same Wiki.
WikiFairy
Another friendly contributor working to beautify pages on a Wiki.
WikiGremlin
Roughly the opposite of a WikiGnome: somebody wreaking havoc and perpetrating sometimes intelligent but always mischievous and malicious edits. Clearly a variant of vandalism.
soft security
...

The concept of WikiGnomes and WikiFairies may or may not have sprung into existence on the Portland Pattern Repository's Wiki where there are more elaborate definitions. [1] [1]

References

See also

External links