I liga, currently named Fortuna I liga due to its sponsorship by Fortuna, is the men's second professional association football division of the Polish football league system, below the Ekstraklasa and above the II liga via promotion/relegation systems. Run by the Polish Football Association (PZPN) since its inception on 30 May 1948. The league was renamed from Second League to First League in 2008. It is currently contested by 18 teams, from 2002 all clubs onwards must have a licence, issued by the Association.

Poland Ekstraklasa, meaning "Extra Class" in Polish, named PKO Bank Polski Ekstraklasa since the 2019–20 season due to its sponsorship by PKO Bank Polski, is the top Polish professional league for men's association football teams.