Aikido, by and large, is considered to be a modern development of traditional Japanese martial arts with its roots stamping from Aiki-Jiujitsu.
It's founder, Morihei Ueshiba development Aikido (loosely translated as the "Way of Harmony") as a martial way of self-preservation. With the aim of the practitioner to defend themselves while at the same time protecting their attacker from injury.
Much of Aikido's techniques are developed from traditional sword and spear movements and techniques. Consisting mainly of turning, blending and redirecting of an opponents "energy" or force, finishing off with a pin or a throw.
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 formulated by Ueshiba and most have concern for the well-being of the attacker.