Virginity
Virginity is when you haven't had sex. Some people want to have sexual activity without losing their virginity, but this is really impossible. A person who has not had sex is called a virgin. Girls have a vaginal corona (hymen) which is usually broken on the first time she has vaginal sex, so some people say a woman is a virgin so long as she still has her hymen, but this is really inaccurate and not very helpful.
I heard of a university professor saying something like, "I don't want anyone who's been laying down naked with someone calling themselves a virgin.". This sounds like it's in the right spirit. I really don't think that having sex is a rite of passage or changes you from boy to man? or from girl to woman.
Virginity is a good thing, and not something to be ashamed of or to be mocked or derided, both boy and girl virginity. (I liked it when characters would celebrate behind the main character's back in the show What I Like About You? when it was revealed that she was still a virgin.)
See also
I think my rite of passage was getting an adult library card.