Nipple stimulation is the touching, rubbing, biting, kissing or licking of the nipples or the area around the nipples, called the areola, for sexual enjoyment. Women usually get more pleasure from this type of stimulation than men, whose nipples are actually more sensitive - and usually not in a good way.
Nipple stimulation can be used as an arousal technique in foreplay or as part of sex. It is even possible for some people to orgasm through nipple stimulation alone. Some people may call this a nipplegasm.