Each type involves a different kind of genital contact with another partner. Even looking at this list can be kind-of embarrassing for some people, but you really need to know this stuff! The five types are:
Some teens are having oral, anal and/or skin-to-skin contact, and they'll absolutely swear that what they're doing "isn't REALLY sex." NOT TRUE! All five kinds of sex require some type of protection against Sexually Transmitted Infections (STIs) and/or the possibility of pregnancy.