Apollo 1: Unfueled systems test. Fire in command module caused death of all three astronauts in less than 30 seconds. Radical practice revision and audit changes NASA methods and conduct permanently [http://en.wikipedia.org/wiki/Apollo_1#Accident].
Apollo 2: Rocket test, stage 1 of Project Highwater [http://en.wikipedia.org/wiki/Project_Highwater]
Apollo 3: Rocket test, stage 2 of Project Highwater
Apollo 4: Final rocket test of first stage engines, Lunar orbit test (unmanned testing module crashes into Moon successfully)
Apollo 5: Atmospheric test of Lunar module engine abort modes.
Apollo 6: Second unmanned Lunar orbit test, testing module successfully returns to Earth
Apollo 7: Manned testing of navigation systems of the Command module in Earth orbit
Apollo 8: Manned Lunar orbit "dry-run", man first orbits the moon
Apollo 9: Manned testing of Service Module, Command Module and Lunar module in Earth orbit
Apollo 10: Manned Lunar orbit, Lunar module deployed but never landed. Testing for Moon landing deemed complete.
Apollo 11: First manned Lunar landing. Mission on surface duration 2.5 hours.
Apollo 12: Second manned Lunar landing. Mission on surface duration 7.75 hours.
Apollo 13: Mission aborted after explosion en route to the moon, astronauts successfully recovered. Currently holds human altitude record.
Apollo 14: Third manned Lunar landing. Mission on surface duration 9.3 hours.
Apollo 15: Fourth manned Lunar landing. Mission on surface duration 18.7 hours. Due to amount and quality of samples, widely considered to be the most successful mission.
Apollo 16: Fifth manned Lunar landing. Mission on surface duration 20.2 hours.
Apollo 17: Sixth and final (to date) manned Lunar landing. Mission on surface duration 22.1 hours.
Apollo 18: Redesignated for the Skylab Project SkyLab 1. Carried America's first Space station into orbit.
Apollo 19: Redesignated for the Skylab Project SkyLab 2. Carried crew of four as well as provisions to SkyLab.
Apollo 20: Redesignated for the Apollo-Soyuz Test Project.
Apollo 21: Never built, funding cuts led to cancellation.
Apollo 22: Never built, funding cuts led to cancellation.
Apollo 23: Cancelled before planning stage.
Apollo 24: Cancelled before planning stage.