Terms used for sex between two women or two men. The top is the pleasure giver and the one on bottom is receiving. They are not the same as dom and sub because even though many bottoms are subs and tops are doms, there are variations such as service tops and power bottoms. Some people are also versatile, which means they both top and bottom, not to be confused with switch.
(on tinder)
Person a: Hey cutie Person b: so are you a top or bottom?
Person a: don't you think it's a bit early to know that?
A definition for sex. can be for straight or non straight partners. The top is the pleasuregiver(a.k.a the one on the top) and the one on bottom is receiving. (aka the one on the bottom)