Aikido is a Japanese martial art developed by Morihei Ueshiba as a synthesis of his martial studies, philosophy, and religious beliefs. Aikido is often translated as "the Way of unifying (with) life energy" or as "the Way of harmonious spirit." Ueshiba's goal was to create an art that practitioners could use to defend themselves while also protecting their attacker from injury.
Aikido is performed by blending with the motion of the attacker and redirecting the force of the attack rather than opposing it head-on. This requires very little physical energy, as the aikidoka (aikido practitioner) "leads" the attacker's momentum using entering and turning movements. The techniques are completed with various throws or joint locks. Aikido can be categorized under the general umbrella of grappling arts.
Aikido derives mainly from the martial art of Daito-ryo Aiki-jujutsu, but began to diverge from it in the late 1920s, partly due to Ueshiba's involvement with the Omoto-kyo religion. Ueshiba's early students' documents bear the term aiki-jujutsu. Many of Ueshiba's senior students have different approaches to aikido depending on when they studied with him. Today aikido is found all over the world in a number of styles with broad ranges of interpretation and emphasis. However, they all share techniques learned from Ueshiba and most have concern for the well-being of the attacker. This attitude has been at the core of criticisms of aikido and related arts.
The term "do" connects the practice of aikido with the philosophical concept of Tao, which can be found in martial arts such as judo and kendo, and in more peaceful arts such as Japanese calligraphy (shodo), flower arranging (kado) and tea ceremony (chado or sado). The term "aiki" refers to the martial arts principle or tactic of blending with an attacker's movements for the purpose of controlling their actions with minimal effort. One applies "aiki" by understanding the rhythm and intent of the attacker to find the optimal position and timing to apply a counter-technique. Historically, aiki was mastered for the purpose of killing; however in aikido one seeks to control an aggressor without causing harm. Ueshiba is quoted as saying, "To control aggression without inflicting injury is the Art of Peace." A number of aikido practitioners interpret aikido metaphorically, seeing parallels between aikido techniques and other methods for conflict resolution.
Ueshiba envisioned aikido not only as the synthesis of his martial training, but also an expression of his personal philosophy of universal peace and reconciliation. During Ueshiba's lifetime and continuing today, aikido has evolved from the koryu (old-style martial arts) that Ueshiba studied into a wide variety of expressions by martial artists throughout the world.