The Apollo spacecraft was composed of five combined parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth. The expendable (single-use) spacecraft consisted of a combined Command/Service Module (CSM) and a Lunar Module (LM), supported by an emergency Launch Escape System (LES), and a Spacecraft/Lunar Module Adapter (SLA) designed to connect the CSM to the launch vehicle and house the LM.

The design was based on the Lunar Orbit Rendezvous approach: two docked spacecraft were sent to the Moon and went into lunar orbit. While the LM separated and landed, the CSM remained in orbit. After the lunar excursion, the two craft rendezvoused and docked in lunar orbit, and the CSM returned the crew to Earth. The Command Module was the only part of the spacecraft that returned with the crew to the Earth's surface.

The LES and SLA were not actually part of the spacecraft, but were considered part of the spacecraft stack during space vehicle assembly. The LES was jettisoned during launch upon reaching the point where it was no longer needed, and the SLA remained attached to the launch vehicle's upper stage. Two unmanned CSM's, one unmanned LM and one manned CSM were carried into space by Saturn IB launch vehicles for low Earth orbit Apollo missions. Larger Saturn Vs launched two unmanned CSM's on high Earth orbit test flights, the CSM on one manned lunar mission, the complete spacecraft on one manned low Earth orbit mission and eight manned lunar missions. After conclusion of the Apollo program, four CSM's were launched on Saturn IBs for three Skylab Earth orbital missions and the Apollo-Soyuz Test Project.