DKP
Short for dragon kill points, DKP is a point system that originated in the online game EverQuest. Since then, it has been used in many MMORPGs to help players fairly distribute the loot obtained when a large party of players defeats an enemy. For each player that participates in killing a large creature or other large mob, the player earns points, often based on the difficulty and amount of players participating. DKP are kept track of by the guild leader and used to loot creature drops. The player who participated the most gets the most points and be entitled to the rare or otherwise valuable loot first.
Each game and guild has their own method of obtaining and tracking DKP. When joining a guild, talk with the guild leader or review their website (if they have one) for additional information about how they manage DKP.