To promote and archive images of Asian women. The general categories of these images include:
Random Cute Girls
Fat, ugly or diseased shambling horrors can go start their own damn 'booru.
While discussion and suggestions are encouraged, 3dbooru is not a democracy and is ruled with an iron fist by the administrators and moderators. Whining, bitching, moaning and general passive-aggressive tactics will not do you well here.
The name is a play on the term 2-D Complex but signifies that we only accept photos of women, not drawings, CG, sketches or the like. There are other danbooru-based sites a list of which can be found on the Overbooru - http://pinochan.net/overbooru that cater to these tastes including the mother of all booru's and clone sites, Danbooru - http://danbooru.donmai.us.