Whenever I move, that's Aikido.
-O Sensei, Morihei Ueshiba
Aikido is a Japanese martial art created by Morihei Ueshiba (b. 1883, d. 1969). Now referred to as "O-Sensei", or Great Teacher. Ueshiba studied and became an expert in many traditional forms of martial arts, among them kendo and ju-jitsu. In the 1930's, O-Sensei decided to establish his own art, one significantly different from the old schools. This art would eventually become known by the term Aikido.
The word "Aikido" is formed of three kanji (Japanese characters):
合 - ai - joining, harmonizing
気 - ki - spirit, life energy
道 - dō - way, path
Thus, Aikido can be translated as The Way of Harmonious Energy. O-Sensei realized that winning at the expense of another's defeat was not a victory at all. As a result of that revelation, O-Sensei took the martial skills he had mastered, and created from them an entirely new discipline. In Aikido techniques, we blend with our attacker rather than fighting toe-to-toe. There is never direct opposition. Instead, the attacker's energy is redirected or evaded. The attack leads either to a throw or an immobilizing pin, and care is taken to do the least harm possible to the attacker. The attacker learns quickly that he will only hurt himself with his aggression.
Nearly all Aikido movements are circular in nature. Even movements that appear to be direct and straight have spiraling motions involved. Aikido can be extremely vigorous, dynamic, and powerful. It is also very difficult to execute properly, despite what the casual observer might believe in seeing the ease with which an experienced aikidoist throws around his or her partner.
In the end, there is only one way to truly come to know and understand the power of Aikido: