The expansion of the A-League has occurred several times since the league began play in 2005. The A-League was established as the top association football division in the Australian league system, and the only professional and national league of the sport. It was founded in 2004 with eight teams and has since expanded into new markets across Australia and New Zealand. The league is currently contested by 10 teams, although a total of 13 have competed at some stage in its short history.