what make a strong friendship relationship

I think strong friendships all have the same characteristics: trust, generousity and loyalty.
We always say that you should treat someone the way you want to be treated. That is the golden rule as to maintaining a strong friendship. Friendships become the strongest when both of you believe in eachother no matter how many voices there are on the other side. Also, you may have fights but in the end, you are willing to tolerate all the mistakes the other has made. In times of difficulty, you stick up for eachother and choose to stand together in a battle.
Strong friendships need all those admirable qualities, just like a famous American reporter once said: "A friend is one who walks in when others walk out."