XP may refer to any of the following:
Slang often used for describing Microsoft Windows XP.
When referring to a game, XP or exp is also used as an abbreviation in RPGs or MMORPGs for experience. XP is often gained when a player in a game defeats an opponent of similar skill or level. When the player gets enough experience, their level increases.
The Athlon XP is a seventh generation series of the AMD processors. For example, a processor in this AMD series is the Athlon XP 3100+.
XP or xP is also an emoticon with its tongue sticking out.
Game terms, Operating system terms, XP2