Experience points

Experience points (often shortened to XP or EXP) are points which are used to reflect character experience and growth, most often in role-playing games. Experience points may be gained through a variety of means, such as completing a quest or defeating an enemy in combat. The number of experience points gained is usually reflective of the difficulty of the task in which they were earned (for example, defeating a rat will earn far less experience than defeating a boss.)

Experience points are usually gained for the purpose of leveling up.

Activity-based progression
In some systems, such as Xanadu: Dragon Slayer II (1985), Final Fantasy II (1988), SaGa series (1989 onwards), The Elder Scrolls series (1994 onwards), and Grandia series (1997 onwards), progression is based on increasing individual statistics (skills, rank and other features) of the character, and is not driven by the acquisition of (general) experience points. The skills and attributes are made to grow through exercised use.