The jo was also adapted by Morihei Ueshiba, the founder of aikido, to teach the principles of aikido. His use of the weapon is called aikijo. Aikijo resembles jodo in that both involve fencing with the jo, but differs in the nature and purpose of the fencing. Jodo techniques are often faster and sharper because angular attacks and defenses are part of its combat orientation. Aikijo techniques are slower and softer because circular movements can blend [with] attacks and defenses and reduce the attitude of conflict. Inserting and entwining techniques are not found to the same extent in aikijo as they are in jodo, nor are the numerous targets of atemi waza. Aikijo does have jo-taking and jo-keeping techniques, but these are aikido throws in which the jo is incidental to the throw rather than essential to it. Thus, while aikijo is more limited than jodo because it has fewer targets and fewer kinds of movements, it is also much broader in that its application does not depend on a four-foot staff but on the fundamenatal movements of aikido.
D. Zier and T. Lang Jo — The Japanese Short Staff 1985.
The jo is about four feet long and has two parts the tip or kissaki and the butt, base, or ishizuki.
.Just as jujutsu (grappling) became judo, and kenjutsu (sword fighting) became kendo, jojutsu became jodo.