Friendship

I've been thinking about friendships. I have some very good friends. A couple I only know the voice of. Meaning we met online and have kept in contact online and over the phone. One of them I think of as one of my very best friends.
What does it mean to be a really true friend? To me it means to be able to tell my friend anything and be told anything by my friend, even if it hurts a little. If your really good friends can't tell you anything then you really aren't being a good friend then are you. Sure feathers may get ruffled from time to time but if you truly are close then you can get through it all.