Jōdō (杖道), the way of the jō, is the modern practice of the four-foot wooden short staff used against the sword. It is drawn almost entirely from the classical jōjutsu of Shintō Musō-ryū, and it is practised today both as a standardised set and as the deeper koryū from which that set was taken.
From koryū to a standard set
Shintō Musō-ryū jōjutsu is a tradition several centuries old. In 1968 the All Japan Kendo Federation drew up Seitei Jōdō, a standardised group of paired forms taken from that school, so that the staff could be taught, examined and graded widely. The teacher Shimizu Takaji was central both to bringing Shintō Musō-ryū before a wider public and to this standardisation.
A humble stick, truly understood, can answer the sword.
How it is practised
Jōdō is practised in paired kata, one partner wielding the jō and the other a wooden sword, the bokutō. Because the staff has reach and can be used at both ends, it can strike, thrust and sweep, and the practice turns above all on distance and timing against the blade. The aim is control of the swordsman rather than a mere exchange of blows.
Two layers
Many practitioners learn the standardised seitei set, and some go on to the full curriculum of Shintō Musō-ryū. Ryūpedia treats jōdō as a modern way grown from a documented koryū, distinct from but firmly rooted in that older art.
Honesty note
The modern standardisation of 1968 is well documented. The deeper origin in Shintō Musō-ryū, attributed to Musō Gonnosuke, carries its own legendary elements, which are treated in that school's own article.