It’s a giant virtual ball of art! This site is an attempt at communal art, but it also has the appeal of that wall where all the stoners hang out and draw doodles. You can draw what you want, but know that someone can draw over it.
New users start out with a limited amount of ink. If you create something that the site administrators deem to be of value they’ll preserve it for a while, then add it to the hall of fame and you will win unlimited ink.
There have been several large scale projects undertaken by groups to control the ball. In 2006, a large Korean flag was clearly visible and then slowly was changed into a Pepsi logo by competing artists. Read more about the history here.
It’s worth taking a look at this communal project even if you can’t draw at all. Check out the hall of fame for some really interesting pieces.