Anger is an emotion, "subjectively experienced as an aroused state of antagonism toward someone or something perceived to be the source of an aversive event." Three types of anger are recognized by psychologists: One connected to the impulse for self-preservation, occurring when the person or animal is tormented or trapped. The second type of anger is a reaction to perceived deliberate harm doing or unfair treatment by others. Irritability, sullenness and churlishness are examples of the third type of anger which is related more to character traits than to instincts or cognitions.

Modern psychologists view anger as a primary, natural and even mature emotion experienced by all humans at times, something that has functional value for survival. Anger can mobilize psychological resources for corrective action. Uncontrolled anger can however negatively affect personal or social well-being.

The external expression of anger can be found in facial expressions, body language, physiological responses, and at times in public acts of aggression. While most of those who experience anger explain its arousal as a result of "what has happened to them", psychologists point out that an angry person can be very well mistaken because anger causes a loss in self-monitoring capacity and objective observability.

While all philosophers and writers have warned against the spontaneous and uncontrolled fits of anger, there has been disagreement over an intrinsic value to anger. Dealing with anger has been addressed in the writings of earliest philosophers up to modern times. Modern psychologists, in contrast to the earlier writers, have also pointed out the possible harmful effects of suppression of anger.

It has been also shown that the display of anger can be used as an effective manipulation strategy for social influence.