American Airlines - AAdvantage

American Airlines is a major United States airline and the world's largest airline when measured by fleet size, revenue, scheduled passengers carried, scheduled passenger-kilometers flown, and number of destinations served. American Airlines is also a founding member of the Oneworld Alliance.

AAdvantage is the frequently flyer program of American Airlines and is the largest frequent flyer programmer in the world.Through AAdvantage, members are able to redeem tickets, upgrade service class, or obtain free or discounted car rentals, hotel stays, merchandise, or other products and services through partners. 

To join American Airlines' AAdvantage, you can simply register online here.