The TFF First League (currently known under the terms of a sponsorship deal as the PTT 1. Lig) is the second level of the Turkish football league system. The league was founded in 2000 after it was separated from the Turkish Second League Category B during reorganizing Second League, who was second level of Turkish league between 1963–2001. It was founded as the Turkish Second League Category A and started with 20 teams. The number of teams were reduced to 18 the season after, in 2002. The league was renamed TFF First League prior to the 2007–08 season. It was called Türk Telekom Lig A in 2006–2007 season.
Before the 2005–06 season, the top three teams were promoted to Süper Lig and the bottom three teams were relegated to the Turkish Second League Category B. Since the 2005–06 season through 2008–09, the top two teams are directly promoted to the Süper Lig, the teams finishing third through sixth competed in a play-off. The third-placed team played a match with the sixth-placed team, while the fourth-placed team played against the fifth-placed team. The winners of both matches then played against each other to decide the third team that was promoted. In 2009–10 the third team was determined by play-off group games, in which the 3rd, 4th, 5th and 6 th teams of normal season played in a one-game league system in a neutral venue. In 2010–11 play-off status changed again and elimination match system came back but this time on a two match (home and away) basis.
The teams can be register with only 3 foreign players and 2 other Turkic country players.