define true friends.

can anyone explain what true friends really are? is it just, telling u that i will be there when u need me? or just, i'll give u a hand when u need help? hahaha. actually, i guess i've also tried before, 说到做不到 ba. that is why, i am afraid to make promises ever since that time. hehe. and to my friends. i hope u all can correct me if i'm wrong. dun just sit quietly without telling me my mistakes. because, i dun wish to lose anyone of u wahahahaha. and also, please define true friends for me :D only if u saw this post hehe