Anger is an emotional state that may range in intensity from mild irritation to intense fury and rage. Anger has physical effects including raising the heart rate and blood pressure and the levels of adrenaline and noradrenaline. Anger is a (physiological and psychological) response to a perceived threat to self or important others, present, past, or future. The threat may appear to be real, discussed, or imagined. Anger is often a response to the perception of threat due to a physical conflict, injustice, negligence, humiliation or betrayal among other contentions. The expression of anger can be through active or passive behaviours. In the case of "active" emotion the angry person "lashes out" verbally or physically at an intended target. When anger is a "passive" emotion it is characterised by silent sulking, passive-aggressive behaviour (hostility) and tension. This new book presents leading-edge research in this field.