There are 17 different types of smile, according to researcher Paul Ekman, and most of them don’t signal what you might think. Only six occur when we’re having a good time. The rest happen when we’re in pain, embarrassed, uncomfortable, horrified or even miserable.

A smile is sometimes believed to be an effective way of manipulating others or distracting them from our true feelings and more often than not, the universal symbol of happiness is used as a mask (worth thinking about while watching the movie Joker).