PvP, or Player versus Player, is a popular element in many games. Pitting strategy, tactics, and skill to the test, players can face off against each other in one versus one combat, to small teams, all the way up to large scale PvP (sometimes called RvR) in which even hundreds can battle at once.
PvP can occur in several different ways. There is open PvP, which takes place anywhere in the multi-player world; competitive PvP, in which players are ranked (often on a ladder system); and realm versus realm, which is large scale and takes place between two factions, usually in MMORPGs. PvP can also be contained to small teams in arenas or larger teams in special instanced battlegrounds.
To become a master of PvP, you'll need to read up and study the best strategies, learn how to specialize (spec) your character for maximum power, and find out how to get the best gear. Only after extensive study and practice can you become a PvP god!