Aikido is a Japanese Martial Art developed by Morihei Ueshiba during the late 1920s through the 1930s. Ueshiba is often referred to as (O-sensei) Great Teacher.
Ueshiba studied several different styles of Jiu-Jitsu, including Tenjin Shin Yo-Ryu, Kito-Ryu, Yagyu-Ryu, Aioi-Ryu, Shinkage-Ryu as well as Judo and Japanese fencing, and incorporated some of these techniques into Aikido.
But the primary art that Aikido is derived from is Daito-Ryu Aiki-Jujutsu. Ueshiba was a student of Takeda Sokaku, the Grandmaster of Daito Ryu Aiki-Jujutsu.
Aikido is primarily a Throwing Art that uses the attacker’s momentum to work against them.
In the early years of Ueshiba’s teaching he taught the Aiki-Jujutsu style that he had learned from Takeda. This system featured a great amount of (Atemi) Strikes to Vital Points, and a more linear approach than later forms of Aikido.
As Ueshiba grew older, he became more skilled and more spiritual in his outlook, and he implemented more changes to the art. Aikido’s techniques became softer and more circular, and the Striking techniques became less important.
Later in life Ueshiba’s personal philosophy became universal peace and reconciliation. Ueshiba’s goal was to create an art that would allow a person to defend themselves, while also protecting their attacker from injury.
Steven Seagal is probably the most well known Aikido practitioner; he is a 7th dan Black Belt.