The dan (段 dan^?) ranking system is a Japanese mark of level, which is used in modern fine arts and martial arts. Originally invented in a Go school in the Edo period, this system was applied to martial arts by Kanō Jigorō, the founder of judo and later introduced to other East Asia countries.

In the modern Japanese martial arts, holders of dan ranks often wear a black belt, those of higher rank may also wear red-and-white and red belts. Dan ranks are still given in arts such as the strategy board games Go, Renju, the art of flower arrangement (ikebana); and the tea ceremony.

The character of Dan (段, dan^?) is used in Japanese to mean step or grade, and is commonly equated with a degree. However, the origin of the Chinese character, spelled duàn in Pinyin, was used to mean "phase". Dan rank is often used along with the lower rank system, Kyū (級, Kyū^?) rank. There are other methods of assessing rank in Japanese martial systems, of particular note is the older menkyo system.

The dan ranking system in go was devised by Honinbo Dosaku (1645–1702), a professional go player in the Edo period. Prior to the invention, top-to-bottom ranking was evaluated by comparison of handicap and tended to be vague. Dosaku valued the then highest title holder, Meijin at 9 Dan. He was likely inspired by an ancient Chinese go ranking system (9 Pin Zhi) and an earlier court ranking system (nine-rank system), although lower numbers are more senior in those systems.

Dan is a name. It refers sometimes to the short form of the name Daniel. Dan, or the acronym DAN may refer to the following:

Rank refers to the relative position, value, worth, complexity, power, importance, authority, level etc. of a person or object, including:

Daniel Irvin "Dan" Rather, Jr. (born October 31, 1931) is an American journalist and the former news anchor for the CBS Evening News. He is now managing editor and anchor of the television news magazine Dan Rather Reports on the cable channel HDNet. Rather was anchor of the CBS Evening News for 24 years, from March 9, 1981, to March 9, 2005. He also contributed to CBS's 60 Minutes. Rather became embroiled in controversy about a disputed news report involving President Bush's Vietnam-era service in the National Guard and subsequently left CBS Evening News in 2005, and he left the network altogether after 43 years in 2006.

Daniel Irvin Rather, Jr. (/ˈræðər/) was born on October 31, 1931, in Wharton County, Texas, the son of Daniel Irvin Rather, Sr., and the former Byrl Veda Page. The Rathers moved to Houston, and Dan attended Love Elementary School and Hamilton Middle School. He graduated in 1949 from John H. Reagan High School in Houston. In 1953, he received a bachelor's degree in journalism from Sam Houston State University where he was editor of the school newspaper, The Houstonian. At Sam Houston, he was a member of the Caballeros – the founding organization of the currently active Epsilon Psi chapter of the Sigma Chi fraternity. After obtaining his undergraduate degree, Rather briefly attended South Texas College of Law in Houston, which later awarded him an honorary Juris Doctor in 1990. In 1954, Rather enlisted in the United States Marine Corps, but was soon discharged because of having had rheumatic fever as a child .

Glenn Anton "Doc" Rivers (born October 13, 1961) is a former professional basketball player and the current head coach of the NBA's Boston Celtics. Rivers was known for his defense while playing in the NBA. His skills as floor general and point guard helped him transition into a coach following his playing career.

Rivers was a McDonald's All-American for Proviso East High School in the Chicago metropolitan area. Rivers represented the United States with the national team in the 1982 FIBA World Championship, in which he was selected as the tournament MVP, despite missing the last shot in the final which could have given the title to his team. After graduating from Marquette University, Rivers was drafted in the second round (31st overall) of the 1983 NBA Draft by the Atlanta Hawks. He spent the next seven seasons as a starter in Atlanta, assisting star Dominique Wilkins as the team found great regular-season success. He averaged a double-double for the 1986–87 season with 12.8 points and 10.0 assists per game. Rivers later spent one year as a starter for the Los Angeles Clippers and two more for the New York Knicks, before finishing his career as a bench player for the San Antonio Spurs.