Some time just past childhood and before adulthood, our peers become our central focus: who likes us, who we like, who we dress the same as, who we wouldn't be caught dead with. It's like the whole world suddenly revolves around our friends.

True friendship, the kind where beyond having interests in common, you also like who is inside, is the only kind that lasts.

But what really makes a peer a friend? How can you tell if you are in it for the perks, or if you also love the quirks? Is it the person or her closet full of clothes and popular friends? The person or his awesome CD collection? Are you just thrown together by circumstance, or is this a bud worth seeing also outside of chemistry class? Does it matter? Of course it does. Here's why:

True friendship, the kind where beyond having interests in common, you also like who is inside, is the only kind that lasts. You can trust that person for sensible advice, to keep your confidences, and are able to laugh together about nothing and everything - and at yourselves.

In high school, I hung out with an unwieldy bunch of kids - - there were a lot of us, and we absolutely had to do everything together. That meant that planning a Saturday night out took most of the evening, by the time everyone was called and consulted. We were all very similar in some ways (we were all more or less clean-cut, "good" kids) and very different in others, but we mainly hung out together for the better part of four years.

Within the group there were about four people with whom I actually felt consistently close over those years. I am still in touch with them, although there are only two who I would actually call my "friends" - because we can still talk openly, as if no time has passed at all. They live far away from me with their families, but it doesn't matter.

That's another thing about true friendship: it transcends time and space.

I wonder now if I would have spent so much time cultivating (and sometimes chasing) so many other relationships, if I would have known how fleeting most of them are.

How much did the "friendship" with the cute, cool, popular but unstable guy over whom I agonized for years (How should I present myself to him so that he'll think I'm cool enough?) really add to my life in the long run? (Answer: Nada.)

Having just a few good friends is important. You need a stress-free place among equals where you can be yourself, vent your concerns, share your lives. (Is this the case with your friends? Check that you don't feel MORE stressed when you are around the people in your posse.)

Of course, larger crowds tend to add a bit of intrigue - who is going out with who (or who wants to be), who is really tight with who, who is posing...

While this can also be fun - hanging out with a group is cool, especially if you have a lot in common with them - remember that not all of the people in this group will necessarily want to hear details when they ask "How are you?"

Herds tend to move, and they also tend to spook easily. How would you fare after a stampede?

True friends are those who are always interesting, and always interested.

They stick with you, and stick up for you.

And they don't talk behind your back, nor do they report to you, with a grin, all of the juicy gossip everyone is spreading about you.

Most of all, good friends add to us, enhance us, and build us up.

Nervous your best friend won't want to be seen with you in your brother's old Duran Duran t-shirt? She probably doesn't. But keep the t-shirt. And find a new best friend.