Until 1996, the league had two levels,
Serie A1 and
Serie A2, and a relegation/promotion system. However, the teams promoted from the second level could also participate in the championship
play-off against Serie A1's first teams. All the clubs play at the same level since then. Before 2018–2019 season, they were split into two divisions called
Girone (or "Groups"). The teams played home and away matches in their
girone and once against the teams from the other
girone. The first three teams in each
girone entered a
double-elimination play-off tournament, which was the only seen in association football world, to decide the championship winners, who qualified for the
UEFA Champions League preliminary phase. In the 2018–2019 season, the rules changed. All the clubs were still split into two
girone. The teams played once against the other teams in the same
girone. The top four teams in each
girone proceeded to group 1 in the second stage, while the others proceeded to group 2. Teams played twice against each team in the same group. The second and the third team in group 2 proceeded to the play-off. The winner of the play-off, the top team in group 2 and the top 6 teams in group 1 proceeded to the final stage. The championship winner qualified for the
UEFA Champions League preliminary phase and the first runner-up qualified for the
Europa League preliminary phase. In the 2020–2021 season, a new format was applied. Now, all the teams play in the same league and play each other twice. At the end of the regular season, the top twelve teams proceed to the play-off tournament, deciding the winner who qualifies for the
UEFA Champions League preliminary phase, and the loser of the final for the Conference League preliminary phase. In the 2023–24 season, the double-round robin format remained, but the play-offs and final were discontinued for the first time in the competition's history. This time round, the team top of the table after every team has played each other twice, are awarded the title thus keeping in line with the majority of most European leagues. The
domestic cup winners qualify for the
Conference League preliminary phase. ==Stadiums==