I see a lot of threads about this sexual activity, heavy petting, analingus, cunnilingus, fellatio, or that activity; but not many (or any) about kissing. With my girlfriend, kissing is, by far, the second most essential part to foreplay. There is a strong bond and it seems to be the only thing that unifies (or strengthens) that bond. The rest, to me, is instinctual and based mostly off of my libido. And by "kissing" I mean oral kissing and kissing on erogenous zones (but not sucking).