BDSM is an acronym covering the practices of bondage and discipline, dominance and submission, sadism and masochism. These groups of activities are not clearly distinguished and include a great variety of activities.
BDSM is distinguished from abuse by the requirement that all activities are safe, sane and subject to informed consent.
In all BDSM there is a degree of compulsion, willingly accepted, in which the participants derive intense pleasure from their activities. While BDSM play does not have to be sexual that is the usual context.