Emotions unfold from an appraisal process beginning with negative stimuli and then focusing on positive stimuli. Emotions are linked to facial expressions that either convey people’s affect (readout hypothesis) or their social motives (behavioral ecology hypothesis), such as tears convey sadness or a plea for help. Facial expressions come from the combination of innate tendencies and cultural display rules. Emotions motivate individuals to achieve the aim of an emotion, such as fear motivates the individual toward safety. Valence and intensity of emotions influence thoughts and decisions. Negative emotions prompt immediate action while positive emotions, like happiness, act like positive incentives. Positive and negative events increase and decrease happiness, respectively. However, people eventually return to their set point of level happiness as if they are on a hedonic treadmill.