Friendship is a relationship of mutual affection between people. [1] . It is a stronger form of interpersonal bond than an "acquaintance" or an "association", such as a classmate, neighbor, coworker, or colleague.
Your friends are people you know well and like spending time with. You can refer to a friend who you know very well as a good friend or a close friend. He's a good friend of mine. A close friend told me about it. If someone has been your friend for a long time, you can refer to them as an old friend. He or she is not necessarily an old person.