In a broad sense, friendship exists between all human beings even though some of them may never know each other all their lives. If yoa are a peasant, you grow crops and provide other people with food. So you are their friend. In return, they will provide you with farming tools and advanced technology. So they are also your friends. Yoar friendship makes your life possible and easier.
Of course, friendship between familiar people is also important. When we are in trouble, we want other people to give us a hand; when we are upset, we need other people to give us comfort and encouragement. Friendship makes life more meaningful and beaatiful.
One important thing about friendship is that it should be consistent and lasting. We should be friendly to our friends even when they are poor and in bad luck. A friend in need is a friend indeed. Real friendship should stand the test of time and hardship.