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For other uses, see Wiki (disambiguation).
The Wikibook [[wikibooks:|]] has a page on the topic of: Wiki Science

A wiki is a web application that allows users to add content, as on an Internet forum, but also allows anyone to edit the content. The term Wiki also refers to the collaborative software used to create such a website (see Wiki software).

Wiki (with an upper case W) and WikiWikiWeb are both used to refer specifically to the first wiki ever created (March 25, 1995). The WikiWikiWeb is part of the Portland Pattern Repository, a section of a Portland, Oregon, web site operated by the company Cunningham & Cunningham. Wiki proponents often spell 'wiki' with a lower case "w". The name is based on the Hawaiian term wiki wiki, meaning "quick" or "informal". Sometimes wikiwiki (or Wikiwiki) is used instead of wiki.


Key characteristics

A wiki (wikiwiki) enables documents to be written collectively (co-authoring) in a simple markup using a web browser. A single page in a wiki is referred to as a "wiki page", while the entire body of pages, which are usually highly interconnected via hyperlinks, is called "the doodle"; in effect, a very simple database.

A defining characteristic of wiki technology is the ease with which pages can be created and updated. Generally, there is no review before modifications are accepted. Most wikis are open to the general public without the need to register any user account. Sometimes session log-in is requested to acquire a "wiki-signature" cookie for autosigning edits. More private wiki servers require user authentication.

Pages and editing

In a traditional wiki, there are 3 representations for each page:

  • The user-editable "source code," which is also the format stored locally on the server. It usually is plain text, made visible to the user only when the edit operation shows it in a browser form.
  • A template (possibly internally generated) that defines layout and elements common to all pages.
  • The rendered HTML code produced by the server on the fly from the source text when a particular page is requested.

The source format, sometimes known as "wikitext," is augmented with a simplified markup language to hint various structural and visual conventions.. Perhaps the most widespread such convention is to use "*" to start a line of text desired to render as bullet-list items. Style and syntax can vary a great deal among implementations, some of which can allow raw HTML tags as well.

The reasoning behind this design is that HTML with its many cryptic tags is not especially human-readable. Making typical HTML source visible makes the actual text content very hard to read and edit for most users. It is therefore better to promote plain-text editing with a few simple conventions for structure and style.

It is also sometimes viewed as beneficial that users cannot directly use all the functionality that HTML allows, such as JavaScript and Cascading Style Sheets. Consistency in look and feel is also achieved, along with some extra safety for the user. In many wiki implementations, an active hyperlink is exactly as it is shown, unlike in HTML where the invisible hyperlink can have an arbitrary visible anchor text.

Wiki syntax (MediaWiki) 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."

<p>

"<em>Doctor</em>? No other title? A <em>scholar</em>? And he rates above the civil authority?"
</p>
<p>
"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&mdash;under the direct control of the Emperor."
</p>

"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."

(Quotation above from Foundation by Isaac Asimov)

Some recent wiki engines use a different method: they provide "WYSIWYG" editing, usually by means of JavaScript or an ActiveX control 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.

Standard

While for years the de facto standard was the syntax of the original WikiWikiWeb, currently the formatting instructions vary considerably depending on the wiki engine. Simple wikis allow only basic text formatting, whereas more complex ones have support for tables, images, formulas, or even interactive elements such as polls and games. Many people switch between wiki engines. Because of the difficulty in using several syntaxes, many people are putting considerable effort into defining a wiki markup standard (see efforts by Meatball and TikiWiki).

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, often a consequence of the original page creation process, but they 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". Note: It is easy for a wiki to render the visible anchor for such links "pretty" by reinserting spaces, and possibly also reverting to lower case.

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 in a wiki are usually created 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.

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 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.

Server-Side versus Client-Side Wiki

By far the most common wiki systems are server-side (Wikipedia is a server-side wiki). In essence, the edit, display and control functions are provided on the server through the wikiengine that renders the content into a HTML-based page for display in a web browser.

A client-side wiki system only requires the server to "serve" wiki files in much the same way as a web server allows HTML files to be retrieved using HTTP. In a client-side wiki system, all the execution required to convert the underlying wiki text into an onscreen formatted display page resides in the client browser. Likewise, the editing tools and functionality reside with the browser.

The client-side wiki system parallels HTML in that the page becomes a rendering instruction for the browser to interpret.

Client-side wiki systems may be little more than a code plugin to traditional web browsers.

Example: Tiddly Wiki

Controlling changes

History comparison reports highlight the changes between two revisions of a page.

Wikis generally practice 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 all the edits made within a given timeframe. Some wikis can filter the list to remove minor edits and edits made by automatic importing scripts ("bots").

From the change log, other functions are accessible in most wikis: the Revision History showing previous page versions; and the diff feature, highlighting the changes between two revisions. Using the Revision History, an editor can view and restore a previous version of the article. 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 listed on the "Recent Changes" page and, if it is an unacceptable edit, consult the history, restoring a previous revision; this process is more or less streamlined, depending on the wiki software used.

In case unacceptable edits are missed on the "Recent Changes" page, some wiki engines provide additional content control. It can be monitored to ensure that a page, or a set of pages, keeps its quality. A person willing to maintain pages will be warned of modifications to the pages, allowing him or her to quickly verify the validity of new editions.

Vandalism

The open philosophy of most wikis—of allowing anyone to edit content—does not ensure that editors are well-intentioned. Vandalism is a constant problem for wikis.

Spam attacks

Wikis have also been a frequent target of spammers, not because the spammer hopes to induce the wiki's readers into using his products or services, but because the interlinked nature of wikis can make outbound links appear to have high value to search engines (see page rank). The delayed indexing of outbound links, a defense commonly used by search engines against spammers, allows a wiki's editors or participants to remove offending links quickly.

  • Special security measures can be implemented to prevent spamming within Wiki See article here

Suggestions to stop vandalism

There are many ways to stop vandalism. Many public wikis shun mandatory registration procedures; nevertheless, many major wiki engines (including MediaWiki, MoinMoin, UseModWiki, PmWiki and TWiki) provide ways to limit write access. Some wiki engines allow individual users to be banned as editors by blocking their particular IP address or, if available, their usernames; however, many Internet service providers (ISPs) assign a new IP address for each login, so IP bans can often be circumvented relatively easily, and may prevent legitimate users from accessing features.

In addition, improperly configured web servers known as open proxies allow users with fixed IP addresses to circumvent IP bans. To deal with this problem, temporary IP bans are sometimes used—and extended to all IP addresses within a particular range—ensuring, thereby, that the vandal cannot edit pages within a given time. The underlying assumption is that this is often a sufficient deterrent. It may, however, still prevent some non-problematic users from the same ISP from using the service for the duration of the ban.

Another way of reducing comment spam/vandalism is to make use of the new link attribute "rel=nofollow" [1], which is currently supported by some major search engines, including Google.

As an emergency measure, some wikis allow the database to be switched to read-only mode, while others enforce a policy by which only established users—registered prior to an arbitrary cutoff date—can continue editing. In general, any vandalism can be reverted quickly and easily. More problematic, though, are the deliberate insertion of minor or subtle corrections—for example, changing album release dates on discographies.

Many wikis allow pages to be protected from editing. In most wikis, this is used only in extreme and rare cases. Wikipedia's protected pages (see Wikipedia:Protected page), for example, can be edited only by the administrators, who can also revoke the protection (as well as initiate it). Generally, such actions are considered to be against the basic wiki philosophy, and are therefore usually avoided.

Common defense against persistent vandals

A very common defense against persistent vandals is simply to let them deface as many pages as they wish, knowing that the changes can easily be tracked and reverted after the vandals have left. Many vandals vandalize to spread their ideas or opinions. A deterrent to such forms of vandalism is to delete the offending changes as soon as possible. Hopefully the vandals will realize that their political opinions (or whatever it is they want to say) will not get far in such an environment and will leave. This policy quickly becomes impractical, however, in the face of systematic or automated defacements born out of anger, frustration, or ideology.

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 on March 25, 1995. [2] He invented the wiki name and concept, and implemented the first wiki engine. Some people maintain that only the original wiki should be called Wiki (upper case) or the WikiWikiWeb.

Cunningham coined the term wiki after 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." [3] See also: List of computer term etymologies.

In the late 1990s, wikis increasingly were recognized as a promising way to develop private- and public-knowledge bases, and this potential 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 originally was based upon UseMod software, but later switched to its own, open source codebase, now adopted by many other wikis.

In the early 2000s, wikis were increasingly adopted in the enterprise as collaborative software. Common uses included project communication, intranets and documentation, initially for technical users. In December 2002, Socialtext launched the first commercial open source wiki solution. Open source wikis such as MediaWiki, Kwiki and Twiki grew to over 1 million downloads on the Sourceforge repository by 2004. Today some companies use wikis as their only collaborative software and as a replacement for static intranets.

In 2005, the Los Angeles Times experimented with using a wiki in the editorial section of its web site. The Wikitorial project was quickly shuttered as vandals quickly defaced it and features to help distribute administration of the site had been disabled.

Today, the English-language Wikipedia is, by far, the world's largest wiki; the German-language Wikipedia is the second-largest, while the other Wikipedias fill many of the remaining slots. Other big wikis include World66, a wiki travel guide, and Susning.nu, a Swedish-language knowledge base running UseMod software. The all-encompassing nature of Wikipedia is a significant factor in its growth, while many other wikis are highly specialized. Some also have attributed Wikipedia's rapid growth to its decision not to use CamelCase.

Wiki communities

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

The largest wikis are listed at List of largest wikis and Meatball: Biggest wikis.

One way of finding a wiki on a subject in which someone is interested is to follow the wiki-node network from wiki to wiki, or one could take a Wiki bus tour: TourBusStop.

For those interested in creating their own wiki, there are many publicly available "wiki farms," some of which can also make private, password-protected wikis. Socialtext, PeanutButterWiki, SeedWiki, JotSpot, OddWiki, WikiCities, and Wikispaces are seven such services; more at List of wiki farms.

Many wiki communities are private, particularly within enterprises as collaborative software.

References

See also

Look up wiki in Wiktionary, the free dictionary.
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