Thanks for your interest! It's a game-making contest for independent developers, with the purpose of finding out the best indie games of the year. There are two main categories (Pro and Hobby), along with a couple of special ones (like the one for jam entries, as mentioned). A jury will decide the final winners in October, meanwhile there are also polls for the site visitors on some of the games each week. You can enter here: www.thegdwc.com.