Assault is often defined to include not only violence, but any physical contact with another person without their consent. When assault is defined like this, exceptions are provided to cover such things as normal social intercourse (for example, patting someone on the back).
In some jurisdictions, consent is a defence to assault, while in other jurisdictions (most notably England) it is not. This can have important consequences when dealing with issues such as sadomasochistic sexual activity. In England, several men have been successfully convicted of assault for engaging in sadomasochistic activities, even though the activity was consensual.