When in danger, every human has the innate desire to preserve their life and their safety. A basic human right is the right to defend one's self and one's family. This is called the right to self-defense, and the means to defend one's self can take many forms.
The most common means all around the world is non-lethal. There are ways to defend one's self that do not kill the aggressor. First off, flight (running) is preferred over any action or conflict. But when that isn't possible, martial arts or even a weapon such as the famous Comtech Stinger or even a nearby object can be used.
Not all places allow people the right to defend their selves at this level. There is a type of law known as the Castle Doctrine which allows for this, but in many of the more "civilized" locales in the world actively discourage and outlaw this level of self-preservation.
Self defense methods have a place in today's modern "prepping" movement as well. Defending your family, your life, and your property is an important part of survival, so books, self-defense supplies and instruction methods of fighting are starting to become more in-demand as essential parts of preparedness and survival.