Types of behaviour
Human sexual behaviour may conveniently be classified according to the number and gender of the participants. There is solitary behaviour involving only one individual, and there is sociosexual behaviour involving more than one person. Sociosexual behaviour is generally divided into heterosexual behaviour (male with female) and homosexual behaviour (male with male or female with female). If three or more individuals are involved it is, of course, possible to have heterosexual and homosexual activity simultaneously.
In both solitary and sociosexual behaviour there may be activities that are sufficiently unusual to warrant the label deviant behaviour. The term deviant should not be used as a moral judgment but simply as indicating that such activity is not common in a particular society. Since human societies differ in their sexual practices, what is deviant in one society may be normal in another.