Each party needs to be in agreement. It could involve your partner with others as well. To find a friend who is alright with just you is rare, but fun.
NSA, no strings attatched. Basically the other person isn't interested in persuing any kind of emotional attachment (or, more specifically doesn't want you to try to persue anything with him/her)....
Many single men, a lot of single women, lots and lots of people. The internet is full of adult dating sites jam packed full of members looking for sex, one of largest of the new breed is sex contacts...
About 75% of dudes in high school just want as and no relatinship. But others, like me, actually want a relationship. And some may want as, but just want to take it slow