What is a friend in your opinion?

What is a friend? A real and true friend, where can we find? I belive everyone wants to have but sometimes, we do not know they are or not. I used to hear some quote and said that "A friend is like a wine, older is better" Do you agree with me? It is correct! before we know them well, we have to spend time to study together. Sometimes, we have an argument with a friend because of a small and non-sense issue. Only small issue we are able to make angry with a friend and do not want to talk with her or him. In my opinion, a friend is one who is beside me when I am alone and need someone to talk and listen to me. In addition, when I am in troble or sad or depressed, the friend still support and encourage me. I think that it is enough for me.