its pre-paid travel. You purchase a block of several thousand miles at a certain rate per mile. You use it to buy full "Y" fare tickets, and AA deducts the miles from the account. For most domestic trips, it works out to be much cheaper than regular, walk up full "Y" fares. You also get other perks like Admirals Club access, and some "elite" benefits like elite check-in and group 1 boarding.

[This message has been edited by jsmeeker (edited 07-10-2002).]