How does Delta SkyMiles work?

You earn SkyMiles by flying on Delta or its SkyTeam partner airlines: Air France, Korean, KLM, etc. For example, a flight from New York to Fort Myers will earn you 1,080 miles. You can also earn miles for car rentals, hotel stays, and using a co-branded credit card. You also get bonus miles for booking your flights on Delta's website. If you have a co-branded credit card you usually get a double miles for Delta.com purchases. Once or twice per year the cards also offer bonus miles for every day use.

You need a minimum of 25,000 miles to get a free ticket in the Continental US. However, those flights usually depart at 6 a.m. and may take you thousands of miles out of your way, with 6-10 hour layover. You can get more convenient departures, non-stop flights, or better connections, but it will cost you substantially more miles.

You can also use your miles in 10,000 mile increments to pay for all or part of your fare; the rate is 10,000 miles for $100 off your fare. Or, with enough miles and depending on availability, you can get an upgrade to first or business class.

While I wouldn't exactly say you get a more preferential treatment when you get stuck in the airport due to delays, but when you are nice a polite to the agent, and they see that you're a SkyMiles member, they'll use their discretion to get you on an earlier flight or bump you to a better seat. One time, I landed in Atlanta only to see that my connecting flight to New York was canceled. I had to get re-booked on another flight. The gate agent saw that I had over 100,000 SkyMiles and re-booked me on another flight in the First Class.

If you have a Delta-America Express card, your first checked bag is free. If you traveling with a group, up to 7 people, and you or someone else in the group has this card, everyone's first checked bag is free.

You may also use your miles to get stuff. There is an online catalog on delta.com.

You earn miles for every trip based on the length of the flight, or by promotional offers. For example, hotel and car rental companies often have links to frequent flier programs. Every major airline has their own credit card program with bonus miles for signing up and miles for using the card.

Frequent flier programs are not "buy one get one free". Most of them require around 20,000 to 25,000 miles for a free trip anywhere in the US, during off peak times. Trips to the Caribbean, Hawaii, require more miles, longer flights even more. If you travel a lot, you have the option of using miles to upgrade to first class.

Another overlooked benefit is that airlines assign priority to passengers based on miles. If you are ever on of a number of people on standby for a flight, the frequent flier gets priority. If there are 4 people on stand by and one open seats, "high miles" gets the seat.

I would suggest you visit www.delta.com for details - and post these questions in the travel section. This is the section for aircraft questions.