If you had to get to the core of the Internet's primary purpose, it would come down to this: the ability to find information and share information with others.
There's no better place to see that mission in action than in wikis, and especially the well-known Wikipedia. A wiki is a website that lets groups of people work together to create and edit bits of information, and then lets anyone who visits the wiki view that information.
That may sound abstract, so let's take the best-known example of a wiki, the Wikipedia at www.wikipedia.org. The Wikipedia, as its name implies, is an huge online encyclopedia that anyone can use and edit. As of this writing, versions of the Wikipedia are available in ten languageswith the English version alone having more than one million entries and constantly growing.
Anyone can create or edit an entry in the Wikipedia; it depends on a kind of vast communal intelligence to be sure that no errors are made or introduced into it. Volunteers constantly check it for errors and many people with special interests monitor entries to be sure that the Wikipedia stays accurate.
How accurate is it? Surprisingly so, at least measured against traditional encyclopedias. In March 2006, the well-respected science magazine Nature performed an in-depth analysis of a wide range of scientific articles from the Wikipedia and the Encyclopedia Britannica, and found that they were about equally accurate. The study found that in the 42 entries it tested, "the difference in accuracy was not particularly great: the average science entry in Wikipedia contained around four inaccuracies; Britannica, about three."
That's not to say that the Wikipedia is not prone to abuse, because it is. There have been some well-publicized problems with the site. For example, one article falsely suggested that a one-time assistant to Senator Robert Kennedy may have been involved the senator's assassination. Additionally, podcasting pioneer Adam Curry was accused of editing the podcasting entry to remove references to the work of his competitors. There have been other instances as well. Because of this, some high school and college teachers warn their students not to rely solely on the Wikipedia, and some even ban its use outright.
The Wikipedia is the best-known wiki in the world, but it's far from the only wiki. For example, there is the Wikispecies (http://species.wikipedia.org/wiki/Main_Page), a wiki about the species of life on earth; the Wikiquote (http://en.wikiquote.org/wiki/Main_Page), a wiki of quotes; and the Wiktionary (http://en.wiktionary.org/wiki/Main_Page), a wiki dictionary.
Wikis are making their way into the corporate world as well. Companies have set up internal wikis for providing technical help and support, to help collaborate on work, and for many other purposes as well. Expect that in the future, wikis will be used even more as well.