Sumo is a form of competitive full-contact wrestling where a rikishi (wrestler) attempts to force his opponent out of a circular ring (dohyō) or into touching the ground with any body part other than the soles of his feet (usually by throwing or pushing him down).

The sport originated in Japan, the only country where it is practiced professionally. It is considered a gendai budō, which refers to modern Japanese martial art, but the sport has a history spanning many centuries. Many ancient traditions have been preserved in sumo, and even today the sport includes many ritual elements, such as the use of salt purification, from Shinto.

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