Idea came from Albert Mehrabian. It is "perceived distance" or closeness. What you do to make people feel closer to you.
People are drawn toward people they like, evaluate higher, and prefer, and avoid or move away from things they dislike, evaluate negatively, or do not prefer
Idea of promoting affiliation, affection, warmth. We do this through: Touch, proximity, gestures, body positions, direct body orientation, forward lean