Coercion is the practice of forcing another party to act in an involuntary manner by use of threats or force. It involves a set of various types of forceful actions that violate the free will of an individual to induce a desired response, for example: a bully demanding lunch money from a student or the student gets beaten.
These actions may include extortion, blackmail, torture, threats to induce favours, or even sexual assault. In law, coercion is codified as a duress crime. Such actions are used as leverage, to force the victim to act in a way contrary to their own interests.
Coercion may involve the actual infliction of physical pain/injury or psychological harm in order to enhance the credibility of a threat. The threat of further harm may lead to the cooperation or obedience of the person being coerced.
In psychological coercion, the threatened injury regards the victim's relationships with other people … threats to husbands, wives, children, brothers, sisters etc
The most obvious example is blackmail, where the threat consists of the dissemination of damaging information. However, many other types are possible e.g. "emotional blackmail", which typically involves threats of rejection from or disapproval by a peer-group or creating feelings of guilt/obligation via a display of anger or hurt by someone whom the victim loves or respects. Another example is coercive persuasion.
Nasty thing that.