How do air miles work?

I want to know what are bonus air miles or sky miles, and how do they work?

• Answer:

  Airlines and credit cards have loyalty programs where you can accrue 'miles' or 'points'. When you accumulate enough points, you can cash them in for free flights, seat upgrades, and in some cases vacations. Each airline has a different program, I've included several links below. When you fly certain amounts of miles with a particular airline, you gain 'elite' status, which allows you privileges, like getting on the plane first, priority for upgrades, faster mileage accumulation, etc. These perks are used by the airline to gain your loyalty. Some credit cards are connected with a particular airline (like Citibank and American) so you can accumulate points on a single airline, and others have their own system where the miles can be applied to any of a set of airlines.