Ordinarily, we would say that a person who has struck another has “assaulted” him. Technically, that is a battery—the unlawful application of force to another person. The force need not be violent. Indeed, a man who kisses a woman is guilty of a battery if he does it against her will. The other person may consent to the force. That is one reason why surgeons require patients to sign consent forms, giving the doctor permission to operate. In the absence of such a consent, an operation is a battery. That is also why football players are not constantly being charged with battery. Those who agree to play football agree to submit to the rules of the game, which of course include the right to tackle. But the consent does not apply to all acts of physical force: a hockey player who hits an opponent over the head with his stick can be prosecuted for the crime of battery.
Criminal assault is an attempt to commit a battery or the deliberate placing of another in fear of receiving an immediate battery. If you throw a rock at a friend, but he manages to dodge it, you have committed an assault. Some states limit an assault to an attempt to commit a battery by one who has a “present ability” to do so. Pointing an unloaded gun and threatening to shoot would not be an assault, nor, of course, could it be a battery. The modem tendency, however, is to define an assault as an attempt to commit a battery by one with an apparentability to do so.
Assault and battery may be excused. For example, a bar owner (or her agent, the bouncer) may use reasonable force to remove an unruly patron. If the use of force is excessive, the bouncer can be found guilty of assault and battery, and a civil action could arise against the bar owner as well.