. >> reporter: at the site's tenth birthday party in london, cofounder jimmy wales says people essentiallyt to share believe. >> when i started wikipedia i was just basically a guy at home in my pajamas, like everyone else typing on the internet and saying, "hey, everybody, doesn't it seem like it would be fun and a cool idea?" >> reporter: proof that it was, wikipedia is still ad free, funded by donations and entirely written by volunteers. in some fields, like broadcasting, for instance, having a personal wikipedia entry is good for the professional profile but it's also a big unnerving because anyone can edit it at any time. i just checked mine and it looks all right. but wikipedia can occasionally be very wrong. in 2008, on the entry for the village of denshaw in england, pranksters wrote that the local sport was sheep hurling. in 2005, a scottish call center worker built an entire false wiki profile of himself as a highly deck rail decorated sold. >> people sometimes do vandalize wikipedia. >> reporter: it's not quite as accurate as the gold standard of the encyclopedia britannica but