The Delta SkyMiles program is the frequent-flyer program offered by Delta Air Lines, which is undoubtedly one of the most valuable in the world, and it has long been one of the principal catalysts driving the company’s impressive success. One of the world’s largest airline loyalty programs by membership, SkyMiles is noteworthy for its ability to offer consumers exceptional deals, mostly through the carrier’s line of cobranded credit cards that it issues through American Express.