This is a ladder diagram, displaying a juggle pattern of 3 balls.
Time goes from left to right. When a ball is at the upper line, it is
held by the right hand. When it is at the lower line, it is held by the
When a ball is thrown, it moves between the lines. (a long move corresponds to a high throw)
Note that the catches and throws are at regular intervals.
Note that as a result, between some throws, a hand is empty for a longer time than between other throws.
Several web-site propose pattern generators (usually called: site-swap generators).
My own contribution is a site-swap generator for poly-rhythms.