Many people think that the word sex only refers to penile / vaginal intercourse. This is a very limited description which excludes GLBT people.
Though everyone has their own ideas about what counts as sex, a lot of people would agree that vaginal, anal and oral sex, are all sex.
Make sure that you and your partner are on the same page about your definitions before you decide to become intimate. If one person doesn't think that sex includes oral sex, then he or she might not mention their experiences with it during a conversation about sexual history. As a result, you might make decisions about safer sex based on incomplete information.