Anger is an emotional state that may range from minor irritation to intense rage. The physical effects of anger include increased heart rate, blood pressure, and levels of adrenaline and noradrenaline. Some view anger as part of the fight or flight brain response to the perceived threat of harm. Anger becomes the predominant feeling behaviorally, cognitively and physiologically when a person makes the conscious choice to take action to immediately stop the threatening behavior of another outside force. The English term originally comes from the term angr of Old Norse language. Anger can lead to many things physically and mentally.
The external expression of anger can be found in facial expressions, body language, physiological responses, and at times in public acts of aggression. Humans and non-human animals for example make loud sounds, attempt to look physically larger, bare their teeth, and stare. Anger is a behavioral pattern designed to warn aggressors to stop their threatening behavior. Rarely does a physical altercation occur without the prior expression of anger by at least one of the participants. 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.
Modern psychologists view anger as a primary, natural, and mature emotion experienced by all humans at times, and as 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. While many philosophers and writers have warned against the spontaneous and uncontrolled fits of anger, there has been disagreement over the intrinsic value of 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. Displays of anger can be used as a manipulation strategy for social influence.