From The Atlantic:
Wikipedia has the potential to be the greatest effort in collaborative knowledge gathering the world has ever known, and it may well be the greatest effort in voluntary collaboration of any kind. The English-language version alone has more than a million entries. It is consistently ranked among the most visited Web sites in the world. A quarter century ago it was inconceivable that a legion of unpaid, unorganized amateurs scattered about the globe could create anything of value, let alone what may one day be the most comprehensive repository of knowledge in human history. Back then we knew that people do not work for free; or if they do work for free, they do a poor job; and if they work for free in large numbers, the result is a muddle. Jimmy Wales and Larry Sanger knew all this when they began an online encyclopedia in 1999.
Reat the rest here.