She's my best/closest friend - we've known each other since we were five.
He's a family friend/friend of the family.
This restaurant was recommended to me by a friend of mine.
[On the] weekend she is free [so] she goes out with friends. (Skills for Life (Entry 1); A1; Urdu)
I've just added Adam as a friend on Facebook.
Roger and I are old friends.
My old friends from Moscow paid [me] a visit in London. (Preliminary English Test; B1; Russian)
I've been friends with Jo for years.
He was really happy too, so we began to be friends. (Preliminary English Test; B1; Spanish)
He finds it difficult to make friends.
He's made friends with a boy in his class called Alex.
Although I didn't know anyone in this club, I immediately made friends with Maria and Rosaria. (Preliminary English Test; B1; Italian)