In this talk I shall try to answer the question, What is emotion? Emotion theorists struggle to understand and make sense of emotion. Some see emotion as the smoke and deduce the fire: there must be something, but they cannot make out what the fire is. It used to be thought of as an evil presence that possessed individuals. Now, emotion theorists think of the precursor to emotion as “mechanisms”, as states of “action readiness”, as “basic” or “universal” emotion and some suggest “ur-emotion”. But the question remains, what is emotion? In answering this question I shall describe how our reactions to emotion cause depression, anxiety, anger, stress, rage and other psychological problems and what can be done about it.