Like "Google", "Wikipedia" has entered the common lexicon. I haven't yet heard anyone say they're going to Wikipedia something but I'm sure that someone, somewhere, is already doing it. Many of us have Wikipedia bookmarked as our "go to" site, the first port of call to get an overview of a topic. The free, online encyclopedia features roughly 17 million articles in 270 languages, all created by a volunteer community. On 15 January this year Wikipedia celebrates its tenth birthday – what had the potential to become disastrously chaotic has become a valued icon, consulted by more than 400 million people every month.

Wikipedia's infancy was far more humble. The entry Astronomer originally simply said: "Scientist whose area of Research is Astronomy." Sweden: "Country in Northern Europe. Inhabitants are called Swedes. Language spoken is Swedish. Capital is Stockholm." Physics: "Physics is a very broad subject."

However, it grew quickly and over the next five years its breadth and depth exceeded traditional reference sources. New language versions were added and the global volunteer community of Wikipedia editors rapidly increased. Wikipedia believes the key to its success is that anyone can edit any article. This obviously presents potential problems where editors may not have the credentials, but the community also seems to be effective at self-monitoring and a note will usually be made if information requires citation.

"It's hard to imagine that it's been 10 years since I first edited Wikipedia," said Jimmy Wales, co-founder of the website. "I remember that first day. I clicked on 'Edit' and I wrote 'Hello World', and that was the beginning of Wikipedia and all the things that have come since then.

"I want to thank everyone who has helped. I want to thank all the people who have edited Wikipedia, who have contributed to this great knowledge base. I want to thank everybody who is reading Wikipedia, who is really engaging with ideas and knowledge. That's what we made it for: we made it for you to read."

To many people, Wikipedia is synonymous with the idea of wikis, and believe Wikipedia was responsible for WikiLeaks. This prompted an entry explaining that wiki is a generic word, referring to any collaborative website.

Wikipedia also experienced some controversy when it was reported that disgruntled writers and editors were quitting at a rate higher than they could be replaced. Wales' response was that his organization was still trying to figure out the "right" number of volunteers, and that if the declining numbers were indeed a problem, it was one that could be corrected.

Wikipedia is operated by the Wikimedia Foundation, a charitable non-profit organization established in 2003 that is entirely supported by donations. It has just completed its most successful fundraiser, with more than 500,000 individual donations totaling more than US$16 million.

In recent years, Wikipedia has branched out and launched a number of sister sites and projects including Wiktionary, Wikimedia Commons, and Wikisource.

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