The definition of Taekwondo can be changed by the era, the purpose, and personal opinion; the ATA organization defines Taekwondo as a martial art that trains people physically and mentally.

Modern society has forced a change in the martial arts purpose. The martial arts were combat methods that originated as physical fitness regimens. As the participants developed advanced skills, their social position was elevated because of their importance to the defense of the community and because of their ability to train the military in their techniques. As you know, that purpose still exists in the world’s military systems, but civilian life is now well protected by laws. Such combat methods are not required for safety and indeed are sometimes considered unnecessarily violent for personal protection.

Taekwondo, in modern society, is taught as a defensive martial art that develops skills in self-protection, physical agility, and mental keenness.

All the martial arts styles are supported by well-thought philosophies, so they develop mental strength while developing the combat method. In that way, each martial art style established its individual self-concept and defined its style. This combination of physical strength and mental training justifies the existence of the martial arts in a law-abiding modern society.

That is why the official ATA definition of Taekwondo is "a martial art that trains people physically and mentally".

Martial Art -- Military/Self-Defense

Physical Fitness -- Physical Activity

Mental Development -- Philosophy

Taekwondo, as you see, is a trinity of these important and distinctive fields.