Experience points, also called simply experience or xp, are a statistic that measures a player character's activities on adventures and is used in character advancement. The accumulation of experience points leads to greater skill and power.
Using experience points[]
Depending on the system, a character may advance either when the accumulated experience points reach a certain threshold (e.g. gaining levels in Dungeons & Dragons) or when the player expends experience points out of a collected pool (e.g. increasing or buying new Traits in Vampire: The Masquerade).
In some games, such as Predation and other Cypher System games, experience points can also function as metacurrency that can be traded.
Earning experience points[]
Experience points (and advancement in general) are one of the most common reward mechanics in role-playing games. Experience points should be awarded when the players or characters engage in activities that the game system wants to encourage.