An experience point (often abbreviated to Exp or XP) is a unit of measurement used in many role-playing games (RPGs) and role-playing video games to quantify a player character’s progression through the game. Experience points are generally awarded for the completion of quests, overcoming obstacles and opponents, and for successful role-playing. In many RPGs, characters start as fairly weak and untrained. When a sufficient amount of experience is obtained, the character “levels up”, achieving the next stage of character development. Such an event usually increases the character’s statistics, such as maximum health, magic and strength, and may permit the character to acquire new abilities or improve existing ones. In some role-playing games, particularly those derived from Dungeons & Dragons, experience points are used to improve characters in discrete experience levels; in other games, such as GURPS and the World of Darkness games, experience points are spent on specific abilities or attributes chosen by the player. In most games, as the difficulty of the challenge increases, the experience rewarded for overcoming it also increases. As players gain more experience points, the amount of experience needed to gain new abilities typically increases. Alternatively, games keep the amount of experience points per level constant, but progressively lower the experience gained for the same tasks as the character’s level increases. Thus, as the player character strengthens from gaining experience, they are encouraged to accept tasks that are commensurate with their improved abilities in order to advance.