Sumo (“striking one another”) is a form of full-contact wrestling where a wrestler (rikishi) 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. Originated from Japan, this martial art form is practiced professionally and is the country’s national sport. In Sumo, many ancient traditions have been preserved, including ritual elements, such as the use of salt purification. Sumo wrestlers wear a traditional loincloth called a mawashi and are required to live in sumo training stables (heya), where all aspects of their daily lives (dress code, meals) are dictated by strict tradition. The highest rank in sumo is Yokozuna, which literally means "horizontal rope" and comes from the most visible symbol of their rank, the rope, worn around the waist.