In common law, battery is the tort of intentionally causing harmful or offensive contact with another person. As distinguished from assault, battery requires an actual contact, not just intent to cause contact.
While the law varies by jursidiction, contact is often defined as "harmful" if it injures, disfigures, impairs, or causes pain. Contact is deemed "offensive" if would offend a reasonable person's sense of personal dignity. Incidental contact that is common in modern life will not generally rise to the level of battery.
Battery need not require body-to-body contact. Any volitional movement, such as throwing an object toward another, can constitute battery. Touching an object "intimately connected" to a person (such as an object he is holding) can also be battery.
There are defenses to battery, including the reasonable necessity of self-defense or defense of others. Additionally, an invidivudal can consent to battery in some situations, as in sports.
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