Dan (rank) is by far the most recognizable symbol to the general public. The highest dan ranks are sometimes reserved for the founder or leaders of a style and only high-ranking students can be promoted to them. For example, only five living people hold a tenth dan in judo and only about thirty-five worldwide have been promoted to the rank since its inception; of those 10th dan promotions only fifteen were conferred by the Kodokan, all of them to Japanese judoka. This has led to upper level ranks becoming extinct in some arts. In other styles, the dan ranks are not the
Judo were called ; and only those of 4th "dan" or higher were called "judoka". (The suffix , when added to a noun, means a person with expertise or special knowledge on that subject). A judo teacher is called . The word "sensei" comes from "sen" or "saki" (before) and "sei" (life) – i.e. one who has preceded you. In Western dojo, it is common to call an instructor of any "dan" grade "sensei". Traditionally, that title was reserved for instructors of 4th "dan" and above. Judo practitioners traditionally wear white uniforms called or . sometimes abbreviated in the west as