Friends

Over the years, you meet so many people, make new acquaintances and some become "friends".
This all-encompassing word includes best buddies, childhood frnds, school frnds, college frnds, different college frnds, office frnds..
What is it that makes friends? I remember in school in the first standard, we had to write an essay, "My best friend" and we were supposed to stick a photograph of our best friend,I remember I had cut some photo from some newspaper/magazine and stuck it :-)
There are some friends whom I hardly meet now, but I always remember them on their birthdays, I may not call, since I am out of touch now, But I do remember the bday..

Different frnds know different sides of the same person.
If you were shy in school, a school frnd meeting you after years will be shocked to see your vivacious personality, I have seen such people myself.

Some frnds are those whom you talk to every day, share stories, share all events
happening in your life, but these people keep changing, in school, there was somebody, in college there was somebody else and now its somebody else...

Some frnds are just "email" or "chat" frnds, you know over the years they have changed jobs, got married, have kids, but never actually met them since years, thanks to googletalk(cant use other messengers) and orkut , such relationships are thriving..

Some frnds are such that I meet them after ages but I can talk to them like we had just talked yesterday, and with some, even after years of frndship, you dont seem to be able to connect...

What makes people drift apart? Why is it that sometimes you need to get to know a friend all over again? Why is it that sometimes the people you give a lot to, dont give back the same?