Established in 1888 'The Football League' originally consisted of 12 teams and as such did not have any 'divisions'. However in 1892 the Football League accepted (or incorporated) teams from the rival Football Alliance. In doing so they created a 'Second Division' for those teams with existing Football League teams becoming the First Division, the "top tier" of English League football.
By 1921, the Football League comprised of four divisions, outside of which many semi-professional and amateur leagues were formed and reformed. All leagues, and divisions of the Football Leagues, operating a system of promotion/relegation to gain admittance to the Football League and progression through the divisions, or regression down and out of the league.
The First Division, or League Division 1 as it was often referred to, remained the highest tier in English football until the creation of the Premier League in 1992.
The Football League itself was consequently re-organised, with the Second, Third and Fourth Divisions now becoming the First, Second and Third Divisions respectively. Thus, the First Division, while still the top level of the Football League, now became the second level of the entire English football league system. This saw Newcastle "promoted" from the 'old' Second division to the 'new' First Division but this is still classified as being "second tier".
As part of a league-wide rebranding the First Division was renamed to the Football League Championship prior to the start of the 2004–05 season, and has subsequently taken on "Title" sponsors and currently (2016) is the "Sky Bet Championship".
NB: Prior to 1976 a system of "Goal Average" was used instead of the current "Goal Difference". The current 'goal difference' being goals scored minus goals conceded. Goal average being goals scored divided by goals conceded.