ASEAN stands for Association of South East Asian Nations, although the AFF also includes East Timor and Australia, which are not members of ASEAN.
Other nations to join have been Cambodia, Laos, Myanmar and Vietnam (all in 1996), East Timor in 2004, and Australia in 2013, although the latter had been considered an invited affiliate of the AFF since their move to the Asian Football Confederation in 2006, since which time they have sent youth squads to the ASEAN Youth Tournaments.
In 1996, the federation ran the first AFF Championship (then known as the Tiger Cup for sponsorship reasons).
The AFF runs the AFF Championship (since 2008 known as the Suzuki Cup for sponsorship reasons) and AFF Women's Championship - both competitions are held every two years and determine the Champions of Southeast Asia.
The AFF also organises the AFF Futsal Championship, AFF Beach Soccer Championship, various age-level international youth football tournaments, the AFF U-16 Championship, AFF U-19 Youth Championship, AFF U-16 Women's Championship and AFF U-19 Women's Championship.
According to wikipedia