Sumo (相撲 Sumō, alternatively 大相撲 Ōzumō), or Sumo wrestling, is a competition contact sport wherein two wrestlers or rikishi face off in a circular area. The sport is of Japanese origin and is surrounded by ceremony and ritual. The Japanese consider Sumo a gendai budō: a modern Japanese martial art, even though the sport has a history spanning many centuries.

The Sumo tradition is very ancient, and even today the sport includes many ritual elements from when Sumo was used in the Shinto religion, such as the use of salt for purification.