The A-League is the top flight football competition in Australia, with 12 clubs participating including one from New Zealand.
The A-League was founded in 2005 following the demise of the National Soccer League, with a view to a fully professional and commercially sound Australian domestic league.
The competition initially featured only eight clubs but has grown throughout its 15-year existence, with some clubs coming and going, but seven of the foundation clubs remain.
The A-League awards both a premier, for first past the post, as well as a champion, for the team who wins the Grand Final which is played at the end of the top six finals series. In 2019-20, all clubs played 26 matches before the finals.
The champion and premier both qualify for the AFC Champions League along with a third side into the qualifiers, while there is no relegation in the A-League.
Traditionally the A-League has run from October to May, although in 2020-21 this will change to December to July as part of a gradual shift to play football in the Australian winter.