The Boeing 727 is a mid-size, narrow-body, three-engine, T-tailed commercial jet airliner. The 727's fuselage has an outer diameter of 148 inches (3.8 m). This allows six-abreast seating (three per side) and a single central access walkway when coach-class (18 inch width) seats are installed.

The first Boeing 727 flew in 1963 and for over a decade it was the most produced commercial jet airliner in the world. A total of 1,831 727s were delivered. The 727's sales record for the most jet airliners ever sold was broken in the early 1990s by its younger stable mate, the Boeing 737. In August 2008, there were a total of 81 Boeing 727-100 aircraft and 419 727-200 aircraft in airline service.

The 727 proved to be a reliable and versatile airliner so that came to form the core of many start-up airlines' fleets. The 727 was successful with airlines worldwide partly because of its capability to use smaller runways while still flying medium range routes. This effectively allowed airlines to attract passengers from cities with large populations but smaller airports to worldwide tourist destinations.

Faced with higher fuel costs (although all major United States airlines phased them out immediately prior to the oil price increases since 2003, lower passenger volumes due to the post-9/11 economic climate, increasing restrictions on airport noise, and the extra expenses of maintaining older planes and paying flight engineers' salaries, most major airlines have phased 727s out of their fleets. Delta Air Lines, the last major U.S. carrier to do so, retired its last 727 in March, 2003. However, the 727 is still flying for smaller start-up airlines, cargo airlines, and charter airlines, and it is also sometimes used as a private means of transportation.