A:A Frequent Flyer Program is offered by many airlines to reward customer loyalty. Typically, airline customers may enroll in the program free of charge; thereafter, they receive one point for each mile flown on that airline. Points (also known as frequent flyer miles) can be redeemed for free air travel and other products or services.

No one should fly on any airline without enrolling in a mileage program if available.

Most airlines now offer frequent flyer programs, and many airlines have formed alliances that permit customers to earn or redeem miles on groups of airlines, e.g. Oneworld Alliance or Star Alliance. Miles can be obtained not just through flying, but can be earned by staying at a particular hotel or renting an automobile from a particular company. Some credit cards offer miles for each dollar charged to the card; there are programs which allow restaurant diners to earn miles by eating at participating restaurants. Some long distance telephone and Internet service providers offer mileage.

Some miles can expire unless there is account activity at least once within a certain time period, say three years.

For very frequent flyers, many airlines have set up elite frequent flyer programs, typically named after precious metals or precious stones.

Elite membership can provide additional benefits such as:

Increased or doubled mileage accumulation;
An unoccupied adjacent seat, if available;
The ability to reserve exit-row seats which have more legroom;
Free or discounted upgrades to first class;
Preference in flying standby;
Preference in not being bumped if a flight is oversold.
Some top-tier elite programs even permit members to reserve space on sold-out flights, in other words these members have the privilege of bumping other (non-elite) passengers! Elite membership is based on the number of miles actually flown and so-called bonus miles earned through credit card purchases don't count. Some airlines will grant elite status to a passenger who has already attained elite status with another airline.

Some airlines offer accelerated admission to their elite programs through the use of challenges: After enrolling in the challenge program, one flies (for example) 15,000 miles within three months and attains a top-tier membership normally reserved for persons flying 50,000 miles per year.

As of this writing in 2003, some airlines are facing financial difficulties and many frequent flyers fear their miles could be wiped-out in a bankruptcy court proceeding. However, the most recent airline bankruptcy, that of TWA, resulted in TWA's assets being purchased by American Airlines -- which agreed to honor TWA miles.