The English Football League Championship (often referred to as the Championship for short or the Sky Bet Championship for sponsorship reasons, and known as the Football League Championship from 2004 until 2016) is the highest division of the English Football League (EFL) and second-highest overall in the English football league system after the Premier League. The league is contested by 24 clubs. Each season, the two top-finishing teams in the Championship are automatically promoted to the Premier League. The teams that finish the season in 3rd to 6th place enter a playoff tournament, with the winner also gaining promotion to the Premier League. The three lowest-finishing teams in the Championship are relegated to League One.
The Championship, which was introduced for the 2004–05 season, was previously known as the Football League First Division (1992–2004), and before that as the Football League Second Division (1892–1992). The winners of the Championship receive the EFL Championship trophy, the same trophy as the old First Division champions were handed before the Premier League's inception in 1992. Similar to other divisions of professional English football, Welsh clubs can be part of the division, making it a cross-border league.
The Championship is the wealthiest non-top flight football division in the world and the ninth richest division in Europe. With an average match attendance for the 2018–19 season of 20,181, the Championship had the highest per-match attendance of any secondary league in the world, with only nine top-flight leagues known to have higher attendance figures.
Barnsley have spent more seasons at the second level of English football than any other team and on 3 January 2011 became the first club to achieve 1,000 wins in the second level of English football with a 2–1 home victory over Coventry City. Barnsley are also the first club to play 3,000 games in second-level league football (W1028, D747, L1224). Currently, Nottingham Forest and Derby County hold the longest tenure in the Championship, last being out of the division in the 2007–08 season.
Wikipedia — https://en.wikipedia.org/wiki/EFL_Championship