Aikido is a defensive way of unarmed combat, created in the '20s. A technique to halt or defect an incoming strike. Any limb can be used for blocking, but the arm is used the most. Chi is matter, the life that circulates within the human body.
Martial artists perform exercises to cultivate and strenghten their Chi.
A dojo is a Japanese martial arts training hall. In Chinese cosmology the fundamental elements of the universe are wood, fire, earth, water, and metal. In Western cosmology the elements are fire, water, air and earth. The apparel of martial arts, a light robe with pants that is secured with a belt. The belt represents the martial artist's rank or ability.