These are little pictures kept on the bottom of userlookups that show a user's accomplishments. They can be obtained through a number of methods but there are two main types: Game Trophies and Site Event Trophies.
Game Trophies[]
These are obtained by getting high scores in games. It is usually easiest to obtain one after Score Reset Night.
Some games have a limit to how many points can be scored and you get a gold trophy simply if you can match that perfect score. Some non-flash games such as Cheat! give you trophies if you simply beat levels or rounds rather than beating other players.
Site Event Trophies[]
These are trophies that are given out for participating in certain events and therefore they are all technically retired.
There's always a trophy for participating in Plots as well as the Altador Cup and Daily Dare.