What are the challenges of sites such as Wikipedia?

When Wikipedia began I didn't understand the purpose it was designed to serve. I later found out it was an open source for content, and essentially was somewhat of a more modern online version of the encyclopedia. The one concern I had was that I would at times find incorrect information, and I didn't understand how you can promote the site as a source for information and the information be incorrect. I would then come to understand that anyone could update and edit the information on the site, and the creators were also asking for donations to keep the site going.

Other sites boasting to be better than Wikipedia have arisen over the years. Citizendium is one of those sites. The creators of Citizendium took a different approach and instead of anonymous content providers, Citizendium required their editors to provide their identity. Then there are heads of departments so to speak, that oversee the content posted and make sure the information is from "credible" sources. This format never really took off and was considered a flop by the online community. The Citizendium website is still alive, but until now I had never heard of it and I'm sure most of my peers have never heard of it either.