According to Wikipedia’s About page, Wikipedia is “a free content, multilingual encyclopedia written collaboratively by contributors around the world.”

The very nature of a “wiki” is that it can be edited by anyone who has the proper permissions; and because Wikipedia is completely open, ANYONE can edit ANYTHING (within reason). This is both the strength and weakness of Wikipedia; strength, because an open system invites many qualified, intelligent individuals; and weakness, because that same open system is easy to corrupt with bad information. (source: about.com)

How to use wikipedia?

Wikipedia can be accessed from your address bar (on the browser) by typing www.wikipedia.org. From this site, we can get millions encyclopidias. To use this site, we only need to browse www.wikipedia.org. And then, choose the language which we want to use. This site support many languages. Type about what you want to search in wikipedia and press enter. That’s too simple to use it, you will get complete information about what you have typed.

Beside this, you also can use mozilla firefox or opera web browser. Both, provide search bar. You only need to choose wikipedia as the default search and type about what you want to search. Then press enter. So simple to use wikipedia.