Is a countermeasure that involves defending the health and well-being of oneself from harm. The use of the right of self-defense as a legal justification for the use of force in times of danger is available in many jurisdictions, but the interpretation varies widely.
Self-defense education is part of the martial arts industry in the wider sense. self-defense courses are marketed explicitly as being oriented towards effectiveness and optimized towards situations as they occur in the real world. There are a large number of systems taught commercially, many tailored to the needs of specific target audiences (e.g. defense against attempted rape for women, self-defense for children and teens).