Wikipedia isn't a reliable source of information. Nothing out there is 100 percent reliable, but the nature of Wikipedia, the fact that anyone can add or modify info, means that it's particularly prone to errors, intentional or not.
But the nature of Wikipedia is what makes it more accurate in some ways than any other information source, since anyone can verify what's written on the site, fix errors or propose changes.
The catch is that it doesn't happen overnight. In fact, in some cases, it may take five years for an error or false information to be fixed, but perhaps that's understandable given how much work was done in putting the false information there in the first place.
Until very recently, Wikipedia was home to an article about the Bicholim Conflict, a year-long battle dating from 1640 to 1641 between Portugal and the Indian Maratha Empire.
The article was even given "good article" status and, at a length of over 4,500 words, it seemed quite detailed. There was only one problem, not one word of it was true.
Wikipedia user ShelfSkewed started looking at the sources cited in the article and quickly found out that they didn't hold up. The books listed didn't exist, articles online linked back to the Wikipedia article, and there were no other mentions of the conflict to be found online.
The article has now been removed, but it endured for more than five years, making it one of the longest living hoaxes on Wikipedia.
However, there are much more obvious and longer running articles that have eventually been deleted, Wikipedia even running a list of the biggest hoax pages.
An article about Gaius Flavius Antoninus, a supposed assassin of Julius Caesar survived for more than eight years before being discovered and removed. Any article that can top that should have been created no later than 2004.