^
Simply a put, a brony is an avid MLP fan, like me and a few others. Some may go as far as to speak like the ponies in the show, e.g. saying "everypony/anypony" instead of "everybody/anybody". Some may even go further as to pair up the characters in a 'romantic' relationship, referred by the community as "shipping" (avoid these if you dislike this kind of stuff), while others would just become
20% cooler by making usual (but awesome) stuff like fanfics, fanarts, and even to stuff like Flash games, Minecraft builds, TF2 mods, 2D MMO's, etc.
Seriously, I think the brony community is just awesome; lots of really talented people from around the world coming together as a result of friendship, you could say.