Wikipedia

Wikipedia (www.wikipedia.org) is a "copyleft" encyclopedia that is collaboratively developed using wiki software. Wikipedia is managed and operated by the non-profit Wikimedia Foundation. In addition to standard "encyclopedic" knowledge, Wikipedia includes information more often associated with almanacs and gazetteers, as well as coverage of current events.

All original material contributed to Wikipedia is deemed to be free content under the GNU Free Documentation License, meaning that it may be freely used, freely edited, freely copied and freely redistributed subject to the restrictions of that license.

Antecedents

The idea of collecting all of the World's knowledge under a single roof goes back to the ancient Library of Alexandria and Pergamon. The modern notion of the general purpose, widely distributed, printed encyclopedia dates from shortly before Denis Diderot and the 18th century encyclopedists.
The idea of using automated machinery beyond the printing press to build a more useful encyclopedia can be traced to H. G. Wells' short story World Brain (1937) and Vannevar Bush's future vision of the microfilm based Memex in As We May Think (1945). An important milestone along this path is also Ted Nelson's Project Xanadu (1960).
With the development of the Internet, many people attempted to develop Internet encyclopedia projects. Free software exponent Richard Stallman articulated the usefulness of a "Free Universal Encyclopedia and Learning Resource" in 1999. He described Wikipedia's formation as "exciting news", and his Free Software Foundation encourages people "to visit and contribute to the site".

Essential characteristics

There are three essential characteristics of the Wikipedia project, which together define its niche on the World Wide Web:

1. It is, or aims to become, primarily an encyclopedia.
2. It is a wiki, in that it can be edited by anyone (except for blocked users, and excluding protected pages).
3. It is open content, and uses the copyleft GNU Free Documentation License.

Policies

Wikipedia's participants (Wikipedians) commonly follow, and enforce, a few basic policies.

Because there are a huge variety of participants of all ideologies and nationalities Wikipedia is committed to making its articles as unbiased as possible. There has been criticism that the systemic bias of individual participants can color the neutrality of an article - see "Neutral Point Of View", below. However, the aim is not to write articles from a single objective point of view — this is a common misunderstanding of the policy — but rather, to fairly present all views on an issue, attributed to their adherents in a neutral way. Of course, establishing a consensus on what views should be thus attributed can often require much (sometimes heated) discussion and debate.
There are a number of article naming conventions; for example, when several names exist, the most common one in the respective Wikipedia language is preferred.
Wikipedians use "talk" pages or other "out of band" methods to discuss changes to articles, rather than discussing the changes within the articles themselves. This marked a break from other wikis of the time, such as Ward Cunningham's WikiWiki.
There are a number of kinds of entries which are generally discouraged, because they do not, strictly speaking, constitute encyclopedia articles. For example, Wikipedia entries are not dictionary definitions, and the wholesale addition of source material such as the text of laws and speeches is generally frowned upon. (However, some of Wikipedia's sister projects, such as Wiktionary and Wikisource, are designed to be repositories for many alternative forms of reference material that do not fit well into Wikipedia.)
There are a variety of sometimes contradictory rules, guidelines, policies, and common practices that have been proposed and which have varying amounts of support within the Wikipedia community. When these proposed rules are violated, the community decides on a case-by-case basis whether they should be more strictly enforced or not.

Software and hardware

The software that originally ran Wikipedia was UseModWiki, written by Clifford Adams ("Phase I"). At first it required CamelCase for links; soon it was also possible to use the current linking method with double brackets. In January 2002, Wikipedia began running on a PHP wiki engine, which used an underlying MySQL database, added many features (and abolished the behaviour of CamelCase words automatically becoming links), and was specifically written for the Wikipedia project by Magnus Manske ("Phase II"). After a while, the site started to slow down to such an extent that editing became almost impossible. Several rounds of modifications to the software provided only temporary relief. Then Lee Daniel Crocker rewrote the software from scratch. The new version, a major improvement, has been running since July 2002. This "Phase III" software is now called MediaWiki, and is used by many other wiki projects. Brion Vibber has since taken the lead in fixing bugs and tuning the database for performance.

In late 2003, server outages began to seriously diminish the productivity of Wikipedia contributors. Many reported difficulty editing articles as a result of time-outs and severe slowness. This was due to congestion on the single server that was running all the Wikipedias at the time.

As of June 2004, the project runs on nine dedicated servers, located in Florida. This new configuration includes a single database server and four web servers, all running Fedora Core. The web servers serve pages as requested, performing page rendering for all the Wikipedias. To increase speed further, rendered pages for anonymous users are cached in a filesystem until invalidated, allowing page rendering to be skipped entirely for most common page accesses. Cached requests are served by two Squid servers; the new servers are linked via two file system NFS servers (one primary and one backup — the primary NFS server is currently also the email server).

Downloading the database

Anyone who wishes to use Wikipedia's open content may at any time download a nearly-current version of the entire article database to use for any purpose, within the terms of the GFDL.