Aggression refers to a range of behaviors that can result in both physical and psychological harm to oneself, other people, or objects in the environment. The expression of aggression can occur in a number of ways including physically, verbally, mentally and emotionally.Psychologists also distinguish between two different types of aggression: impulsive aggression (typically unplanned and characterised by strong emotions, normally anger); and instrumental aggression (usually carefully planned with the intention of achieving a goal).