Apollo was designed and initially used in American efforts to send a man to The Moon. After several boilerplate designs were flown on Saturn 1 rockets, the first Apollo spacecraft was scheduled to fly in February 1967, flown by Virgil Grissom, Ed White, and Roger Chaffee, however on the 17th January, the spacecraft caught fire on the launch pad, killing the astronauts. The first manned flight was Apollo 7, launched in 1968, on a Saturn 1b rocket. This was followed by Apollo 8, which became the first manned spacecraft to orbit The Moon, in December 1968. Apollo 9 tested the Lunar Module, and Apollo 10 was a "dress rehearsal" for the manned landing. This landing was Apollo 11, and on July 20th 1969, Neil Armstrong became the first man to walk on the Moon.
This was followed by another five successful landings, from six attempts. The failure was Apollo 13, which was forced to abort after an oxygen tank in the service module exploded whilst in flight, crippling the spacecraft. The crew made a free return trajectory around The Moon, and safely returned to Earth, having used Aquarius, the Lunar Module, as a lifeboat. The final three missions carried a Lunar Rover, to allow the astronauts to cover more ground. All missions to The Moon, plus Apollo 9, were launched by the largest manned launch vehicle ever built, the Saturn V.
After the last Moon landing, Apollo 17, surplus equipment was used for two more projects. The first, Skylab, was America's first, and to date only, space station. It was made from the second stage of a Saturn 1b rocket, (commonly confused with the third stage of a Saturn V, as the two were nearly identical) which was placed into earth orbit by the last Saturn V in 1973. Over the next two years, three crews flew Apollo spacecraft to the station, and despite serious malfunctions with the station, caused by the forces involved at launch, and an RCS malfunction on the second manned flight, these were successful. Despite attempts to reboost it for future use by the Space Shuttle, Skylab re-entered Earth's atmosphere and burned up in 1979. The other project was the ASTP, or Apollo-Soyuz test project, which involved the rendezvous and docking of an Apollo CSM with a Soviet Soyuz spacecraft, in orbit. It was the last flight of Apollo, and it is considered to have demonstrated that the Soyuz - which is still in use today - was inferior to the Apollo.
The Apollo spacecraft was made up of three modules, the command module, or CM, housed the astronauts, the service module (SM) contained life support systems, and the engine that would take the spacecraft in and out of Lunar Orbit. Collectively, these two modules were known as the CSM. All missions except Apollos 7, 8, ASTP, and Skylab, carried a Lunar Module, or LM as well. This was a two-man lander, designed to transport the astronauts to the Moon's surface, and bring them back again. As mentioned above, on Apollo 13, the LM was used as a lifeboat, after the failure of the SM.