Understanding the crime triangle is fundamental in developing an effective strategy for self-defense. Three things must be present for a crime to occur: desire, ability and opportunity. If any one of these is removed from the triangle a crime cannot take place.
Obviously we cannot control criminals. There will always be those with the desire and ability to carry out crimes. What we can control is the opportunity. With a little knowledge, we can make ourselves hardened targets and take the opportunity away from criminals.