What counts as sex?

Jocelyn
With lesbians I understand oral/fingering/strap on/grinding and all that count as sex. (Correct me if I'm wrong) What I don't understand is that straight sex is just penis in vagina. Does grinding/oral/fingering count for straight couples sex?  Can couples orgasm without having having sex? (Not mutual mastubation)  sorry if I sound clueless :)