Why are hugs comforting?

Earlier today a bunch of friends and I were talking during a water break, and one of them looked really sad. They weren’t, they were mad, but I thought “Maybe he just needs a hug.” Then I realized how weird that is that that’s the first thing I think when people are sad. And then I thought of this question. Hugs comfort me, and they comfort most people, but the thought of it seems very unappealing to me. I feel like when I’m sad, the last thing I would want is to be squeezed by someone, but when I actually am sad the first thing I want is a hug. So why are hugs so comforting?