What is a friend?

What is a friend?
A friend is someone who supports me everytime.
A friend is someone who cares me every time.
A friend is something I can't describe on a pen.
A friend is someone who can keep me warm every time.
A friend is someone who likes to share anything with me.
A friend is someone who makes me happy when I'm sad.
A friend is someone who loves me and knows me.
That's a friend!