In this chapter the author introduces the families of emotions, sadness, anger, fear, joy, guilt, shame, disgust, envy, and jealousy, and describes their differing functions. There is then a description of how the signature feature of each emotion plays out in the body through various domains – facial expression, temperature, posture, gesture, breathing, muscle tone, voice tone, actions in the environment, and interpretations. There is an explanation of emotion theory – how only one emotion can be experienced at a time, and the difference between an emotion being understandable and one that is justified by the facts.