Knowing that your commitment to each other is always by choice. Giving freely when appropriate and taking graciously when needed. Divining each other's thoughts and feelings easily and often. Winning and losing do not matter to real friends. Friendships are not instantaneous, they are earned.
Friendships withstand the storms and upheavals of time.
Friendships surpass the trite boundaries of acquaintanceship. Friendships often develop with improbable people at unlikely times. Friends know the difference between image and substance. Friends bask in the glow of the other's triumphs. Friends will be there when you need them.