Wikipedia - The biggest, free-content, encyclopedia on the internet and one of the top 100 websites in the world. It is also the most popular example of a Wiki (How Wikis Work). This unique online encyclopedia allows users to log on and become contributors. As a result many articles are written by the foremost experts in a field with lots of current information. Unfortunately, some articles are also poorly written and may contain incorrect information. This has led to several controversies.
The website has often been criticized for inaccuracies by educators (some examples here). Even the co-founder of the website, Larry Sanger has publicly stated that: "While Wikipedia is still quite useful and an amazing phenomenon, I have come to the view that it is also broken beyond repair." Here is a link to Wikipedia's response to the question of:
No matter how you feel about it, there are some good uses for a site like Wikipedia. For example, use Wikipedia to research the most recent developments in technology. Because of the way it is edited it can be quickly updated with the most recent information about technological developments long before more traditional reference sources can even start to make updates. It can also be useful in pointing a researcher towards more reliable sources of information. Most Wikipedia entries include several links to outside websites that contain additional information, just go to the bottom of the page to see them. One also has to admit that the site is well laid out, easy to use, and has a pretty efficient search engine. At the very least educators should become familiar with it just as they should become familiar with any web phenomenon that affects their students' learning.
A few years ago there was a research study that compared Wikipedia to Britannica for accuracy. The study, which was published in December of 2005, showed Wikipedia to be more accurate that Britannica. You can read about the results here:
Recently the co-founder of Wikipedia has founded a new website called Citizendium where he hopes to improve on the Wikipedia model by adding "gentle expert oversight" and requiring contributors to use their real names. Other internet resources are being developed like Google's Knol and Scholarpedia and Veropedia. There's even an online global map where you can enter information about geographic locations called Wikimapia. In an effort to make a free online and downloadable encyclopedia a not for profit organization in the United Kingdon, SOS Children, created Wikipedia for Schools which claims to be an academically editied version of Wikipedia for students to use. Each of these projects offers a different model for verifying information and they each have strengths and weaknesses, but they all represent a uniquely human ambition to somehow catalog human knowledge online.
For more thoughts on the controversies surrounding Wikipedia here's an article on the topic by Bill Platt.