Everyone has a reason for befriending someone. It can be for the spur of the moment, the fact that two people have a lot in common, it could be to nurse an insecurity or to fit in with the kids at school. You get the point.
On top of that, when it comes to choosing friends some people are critical while others are open to anyone.
As for me, I've had bad experiences with people in the past, online and in reality. It's caused me to become an introvert and I always feel that people have their own agenda when they befriend me. Because of this, I take friendship very seriously (that's why, for example, my friends list on the MLP Forums is always being cleared of people every few days).
To sum it all up, to me friendship is sacred, a bond that should not be taken lightly. Maybe I'm just overly sensitive but whatever.
So what do you all expect out of a friendship and how important is a friendship to you?