Every major airline in the United States has a miles program or equivalent points program that allows passengers to pay for flights using miles, as of 2015. Travelers can accumulate miles by securing a frequent flyer membership number or through other promotions.
Members of frequent flyer programs generally receive one mile for each mile flown with that airline. After miles are accumulated, they can be turned in for free flights with that carrier. Redemption costs range from as little as 12,500 miles for domestic one-way economy class tickets to several hundred-thousand for international round-trip first class tickets.
In addition to earning miles by flying, members often accumulate miles with airline-affiliated credit cards. Along with large bonuses for signing up--sometimes as large as 50,000 miles--mileage cards offer cardholders benefits for each dollar spent, usually between one and three miles per dollar spent.
Along with free tickets, some airlines grant elite status to flyers who meet certain thresholds, such as flying more than 100,000 miles per year. Elite status comes with benefits like free access to lounges, complimentary meals and more frequent upgrades.
Frequent flyer programs and related credit cards are an important part of the airline industry. They are designed to increase flyer loyalty and to lure passengers from competitors by providing superior benefits.