• Most commercial airline companies offer frequent flyer programs to reward loyal customers.airplane image by Clarence Alford from Fotolia.com
  
  Frequent flyer programs are programs offered by airlines to maintain customer loyalty by offering rewards when travelers reach certain travel milestones. For example, many airlines offer free flights when frequent flyer customers travel a specified amount of miles or number of flights with the company. There is no program that is "the best" per se; if there was, everyone would fly on that airline all the time. However, with some programs you can earn rewards more easily than you can with other programs.
  
  

Continental OnePass

• Continental's OnePass program accumulates miles for program members, which members can then redeem for free flights. One mile flown on the airline equals one mile earned. What sets this program apart from others is that it requires fewer miles for a free round trip flight in the continental U.S. While most programs require 25,000 miles to earn a free flight, Continental's OnePass only requires 20,000 miles, as of September 2010. In other words, once you have flown 20,000 miles on any Continental flights, you are entitled to a free flight on Continental from anywhere in the mainland U.S. to anywhere in the continental U.S., Canada or Alaska. You must join the program to get credit for miles, which you can do on Continental's website.
  
  

Southwest Rapid Rewards

• Southwest Airline's Rapid Rewards program operates a bit differently than other programs and can be advantageous to frequent travelers. The Southwest program allows you to accumulate points, and not miles. You earn one point for each one way flight on Southwest, and two points for each round trip flight. Once you earn 16 points within a two year period, you earn a free flight anywhere Southwest flies. This program is especially advantageous for frequent fliers who travel short distances; it does not matter how long your flight is, so people who fly short distances with Southwest earn just as many points as people who fly long distances. The program also allows you to accumulate points through credit card usage, car rentals, hotel stays and purchases from certain retailers.
  
  

Delta SkyMiles

• Delta Airlines offers its SkyMiles program, which allows passengers to accumulate miles, similar to Continental's program. The Delta SkyMiles program awards a free flight within the continental U.S. after earning 25,000 miles, which is the same as most other carriers. However, what sets this program apart is the miles needed for flights to Hawaii and international destinations. While most airlines require 40,000 or more miles to earn a round trip flight to Hawaii, Delta only requires 35,000. Similarly, most airlines require 35,000 miles to fly to Mexico or the Caribbean, but Delta only requires 30,000. Of all the major U.S. airlines, Delta requires the fewest miles for a round trip flight to Southern South America and Europe (50,000 for either). You can sign up for the program on Delta's website.