Tease and denial is a term that describes a form of erotic denial where the partner who is dominant practices control over the partner who is submissive.
To put more context to it, tease and denial is a situation in which one of the partners is stimulating the genitals of the other partner until the stimulated partner reaches a point where orgasm is almost imminent. Just when the subject is brought to the edge of orgasm, the other partner reduces the stimulation or stops the process completely. Then, the teasing and denial process repeated over and over again, not allowing the stimulated partner to reach orgasm.
There are plenty of ways of efficient BDSM teasing. Reasonably, sexual activity and intercourses are a frequent way of BDSM tease, but there also are a number of sex toys the couple can use for better stimulation.
When it comes to teasing and denial, there is also something known as "ruined" orgasm. Such ejaculation happens before the person who is stimulating intends, and it is considered to be far less enjoyable than normal.
As with the majority of sexual performances and plays, there is also a psychological element attached to the teasing and denial. In the cases where a BDSM teasing is repeatedly used on a person to the point of orgasm without release, there is a chance of psychological need or intense arousal afterward.
Because of this component, the partners should always communicate with each other about the practice so that the tease and denial can serve its purpose properly.