Fellatio (also known as fellation, a blow job, BJ, giving head or sucking off) is an act of oral stimulation of a male's penis by a sexual partner. It involves the stimulation of the penis by the use of the mouth, tongue, teeth or throat. The person who performs fellatio can be referred to as the giving partner, and the other person is the receiving partner. Fellatio is regarded by many as an erotic act in its own right and a physically intimate act. For many males, it is a turn-on which may be used by the giving partner to initiate foreplay and sexual arousal prior to sexual intercourse. The act may also be performed for the sexual gratification derived by the male receiving partner and can be continued until orgasm and ejaculation of semen.
Fellatio is also sometimes practiced when sexual intercourse can create a physical difficulty for a sex partner. For example, it may be practiced during pregnancy instead of vaginal sex by couples wishing to engage in intimate sexual activity while avoiding the difficulty of vaginal intercourse during later stages of pregnancy.
Some people have negative feelings or sexual inhibitions about giving or receiving oral sex, and may refuse to do so. On the other hand, there are reports that some people use oral sex as a means of preserving virginity, especially in the case of adolescent girls who fellate their boyfriends to create and maintain intimacy while preserving their virginity and/or avoiding pregnancy. Other reasons given for the practice among adolescent girls are peer-group pressure and as their introduction to sexual activity.
Some people regard the receiving partner as being in a position of psychological if not physical vulnerability, and thus is potentially weaker. Bringing a person to climax is considered by some to be a form of exerting control over that person's physiology and emotions.