There are, however, rules. The kiss is the main thing. A certain amount of touching is permissible, but of the neck-stroking, running-hands-through- hair ilk; groping does not enter into it. "Snogging is incredibly sexy, and probably at its sexiest when it's an act in itself and not foreplay," says Emma, 30, and hailed by respectful exes as "one of the all-time great kissers".
"It's such an enjoyable way to pass the time; there's no guilt or trauma involved, you don't have to worry that he won't respect you later. It's a way of being intimate without giving away too much of yourself, and of course it's completely safe.
"All hands should be in the neck and face area. Any further down and you're tempted to rip the other's clothes off, which is sex and not the same thing at all. By kissing you can discover all sorts of erogenous zones: I go mad if someone touches the back of my neck, for instance."
The per capita snog rate is definitely on the rise, says the counsellor Tania Pullen. "Within the last few months, I've been aware of an big increase in snogging in public. They weren't teenagers either. They were normal people. I don't think that we've got more demonstrative or less inhibited, it's just that snogging is now a way of making a fashion statement; it says, 'I'm cool. I can let myself go but not in a vulgar or dangerous way.' It's a kind of knowing wink."
Snogging can indeed mean a good time is had by all, without any of the physical or emotional messiness of going further. "We snog a lot at clubs and parties, it's just a nice thing to do," says Suzanne, 19. "When I was at school it was a really big deal and it would be all 'Ooh, guess who snogged who last night!' but now it's just quite normal and no-one comments. Snogging is just snogging and doesn't mean anything else is promised. Boys know that's the way it is."
And you can also allow yourself a snog on the side if you have a regular partner, without feeling too bad; it's not as if (theoretically) it's any more than a bit of kissing, after all. "I wouldn't feel so bad about snogging someone other than my girlfriend, as long as that's all it was," admits Tom, 23. (When put to the test, the defence "It was only a snog" does not always hold a lot of water.)
Some partners, though, are remarkably tolerant (or possibly blind). "I once tried to provoke my ex-boyfriend into chucking me by snogging somebody else but he completely missed the point," complained Anne, 24. "I then tried chucking him on the strength of it but he again failed to get my meaning and the whole thing dragged on for ever."
One thing to bear in mind about snogging is that it seems to work best with a semi-stranger. "I've done a bit of snogging in the past," admits Emily, 31. "I once ended up dancing with someone and snogging them at a club; sex wasn't implied, but it was terribly exciting doing this with someone I hardly knew. When I'm in a relationship I tend not to spend much time snogging. It's more incidental kissing; the snogging sessions just don't happen, which is a shame."
Natural as snogging may be, a certain amount of practice is needed. "I've never forgotten my first snog - it was on the 11 November 1983 - mainly because it was such a horrific experience," recalls Henrietta, 27. "I thought he was the best of the bunch, but when he tried to put his tongue in my mouth he acted as if my mouth was a washing-machine and he was going for rapid spin cycle. It took a long time before I came back for another go."
Snogging does show a certain sense of humour. It's jolly and fun. One person who is definitely not a snoggy type is the Princess of Wales. She's a serious and sensitive lover. When she said, "Yes I adored him" about James Hewitt she revealed a timewarp internal landscape of overwrought feelings and psychotherapy. Snoggers do not sit at home moping. They go out and get snogged.