Delta Air Lines is one of the three largest airlines in the world, roughly on par with American Airlines and United Airlines. It was founded as a crop dusting service in 1924 and began scheduled service in 1929 between Dallas, Texas and Jackson, Mississippi after being bought out by businessman C. E. Woolman. One year later, however, they went out of business, and were unable to resume service until 1934, when they received an air mail contract from the United States Postal Service.

Delta was never a very large airline until the dark days of the seventies, when they began a growth spurt by buying out Northeast Airlines, Western Airlines, and a large portion of Pan Am. After airline deregulation in 1978, they started service to London and Frankfurt, and in 1987 they began service to Tokyo. By the early 1990's, with Pan Am out of business, they were operating one of the largest trans-Atlantic operations in the world.

Today, Delta serves 425 cities in 76 countries with a fleet of 831 aircraft handling 100 million passengers a year. Their largest hub is at Hartsfield Atlanta International Airport: they also have hubs at Cincinnati, Dallas, Salt Lake City, and Orlando, and international gateways at John F. Kennedy International Airport and Los Angeles International Airport.

Delta's fleet breaks down as follows:

27 of these aircraft are currently grounded in the wake of the September 11, 2001 attacks—not for safety reasons, but because of reduced load factors. Another 162 aircraft are currently on order, most of which are new regional jets for Delta's regional subsidiaries, Comair, ASA, ACA, and Skywest.

Delta is also the anchor of the SkyTeam alliance that includes Air France, Aeromexico, Alitalia, CSA, and Korean Air.

Contrary to popular opinion, "Delta" is not an acronym for "don't ever leave the airport." It refers to the delta of the Mississippi River, where the airline originated.