>> The winner of a sumo bout

In addition to its use as a trial of strength in combat, sumo has also been associated with Shinto ritual, and even certain shrines carry out forms of ritual dance where a human is said to wrestle with a kami (a Shinto divine spirit); see Shinto origins of sumo. It was an important ritual at the imperial court, where representatives of each province were ordered to attend the contest at the court and fight. The contestants were required to pay for their travels themselves. The contest was known as sumai no sechie, or "sumai party."

Cross-influence from other nations adjacent to Japan, sharing many cultural traditions, cannot be ruled out as they also feature styles of traditional wrestling that bear resemblance to sumo. Notable examples include Mongolian wrestling, Chinese Shuai jiao, and Korean Ssireum.
The winner of a sumo bout is either:

1. The first wrestler to force his opponent to step out of the ring.
2. The first wrestler to force his opponent to touch the ground with any part of his body other than the bottom of his feet.

There are also a number of other less common rules that can be used to determine the winner. For example, a wrestler using an illegal technique (or kinjite) automatically loses, as does one whose mawashi (or belt) comes completely undone. A wrestler failing to show up for his bout (including through a prior injury) also automatically loses (fusenpai).

Matches consist solely of a single round and often last only a few seconds, as usually one wrestler is quickly ousted from the circle or thrown to the ground. However, they can occasionally last for several minutes. Each match is preceded by an elaborate ceremonial ritual. Traditionally, sumo wrestlers are renowned for their great girth and body mass, which is often a winning factor in sumo. There are no weight divisions in professional sumo, and considering the range of body weights in sumo, an individual wrestler can sometimes face an opponent twice his own weight. However, with superior technique, smaller wrestlers can control and defeat much larger opponents.

After the winner is declared, an off-stage gyōji (or referee) determines the kimarite (or winning technique) used in the bout, which is then announced to the audience.

On rare occasions the referee or judges may award the win to the wrestler who touched the ground first. This happens if both wrestlers touch the ground at nearly the same time and is decided that the wrestler who touched the ground second had no chance of winning as due to the superior sumo of his opponent, he was already in an irrecoverable position. The losing wrestler is referred to as being shini-tai ("dead body") in this case.
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