XP may refer to: Medicine Xanthelasma palpebrarum, a cholesterol deposit in the eyelid Xeroderma pigmentosum, a genetic disorder Computing Windows XP, an operating system Microsoft Office XP, a version of the software suite Athlon XP, a series of AMD microprocessors Extreme programming, a software development methodology XP, a complexity class in parameterized complexity Technology Ilford XP, a chromogenic black and white film made by Ilford Photo Gaming Experience point, a unit for measuring a character's progress in role-playing games Transport Boeing XP-7, a prototype United States biplane fighter of the 1920s Experimental pursuit, a USAAC aircraft designation, used by e.g. the Lockheed XP-38 Lightning Avelo Airlines (IATA code) Other uses Chi Rho, a Christian symbol Experience point, a unit of measurement in role-playing games XP, an emoticon X phrase in linguistic theory