In the US, almost any type of class now offers a "graduation ceremony." There was a time when graduation meant either completing high school or university, but today children who successfully complete kindergarten are given a miniature graduation ceremony, complete with a little "diploma" and a cap and gown.
In the grand scheme of things, though, a traditional graduation ceremony occurs after a student completes four years of high school, or college. There is a ceremony where the students wear caps and gowns, and the dean or principal officially presents each graduating student with their diploma. Traditionally, the graduate at that moment moves the tassel on his cap from one side to the other.