This chapter provides an overview of the mechanics and neurobiology of facial expressions, which are surprisingly complex. It outlines the function and origin of facial expressions and the question of whether facial expressions are universal or culture specific. The chapter shows how facial expressions convey information about the expresser's emotional state and their social motives and intentions. It explores how facial expressions may not just be a product of an emotion state, but may even help create the feeling of an emotion. The chapter shows how this possibility allows for facial mimicry to help us understand the emotions of others. It reviews research into how the body and the voice convey emotion and how all these signals, when combined, are perceived by others. If facial expressions serve a communicative function, other people must be able to recognize them. From an evolutionary perspective, facial expressions of emotions are innate expressions of specific emotional states.