Xperience is a tailored gene-therapy, consumed as a drug in aerosolised form via an inhaler. It is a product of the Sublime Corporation, created from the genetic material of assorted mutants, mostly members of the X-Men (since they have the highest media profile and Sublime intends to market the drug).
A brief snort of Xperience will power up the user with the powers of the X-Man in question for several hours. It appears to be mildly addictive, although it is unclear whether this is a physical effect or merely a psychological one.
Known members of the X-Men whose genetic material was used to create varieties of Xperience include Wolverine, Deadpool, Cyclops, Beast, Iceman, Angel, Emma Frost, Professor X and Jean Grey in both her Marvel Girl and Phoenix incarnations. (But not Adam X. Never Adam X.) However, due to the efforts of the X-Men, Xperience is no longer being created, and only a few stolen samples of it still exist.