FRIENDSHIP - NOT A SUBJECT IN SCHOOL

Friendship is not something learned at school,but by the time you leave- if you have not learned who a TRUE friend IS THEN YOU HAVEN'T LEARNED ANYTHING AT ALL!h!!!

So, what is true friendship?
What are some of the instances that would convince you that this is a true friend?

My friend MIKE thinks its the sacrifices that someone does for the other person without coercion, duress or undue influence of some sorts.... And this prods us to ask
What do you make of the sacrifices a Family member or persons of close relations commits or ommits to do for our sakes,Is it good enough evidence of friendship?
Or better still,How does one decipher the difference between sacrifice Vs obligation?guess will come to that some other day .......