>>11025508Six missions landed on the Moon: Apollo 11 through Apollo 17 excluding Apollo 13, which was forced to abandon plans for landing when their spacecraft was crippled by an explosion in the service module.
Each successful landing worked as follows: the complete lunar module touched down on the Moon's surface with a two-man crew, the astronauts stayed put and did moonwalks (and moondrives, and moongolfing, and moonhammerthrowing) for a day or three, and when they were all done, they took off in the lunar module's ascent stage, which separated from the (spent) descent stage and flew back into orbit to rendezvous with the orbiting Command module. Finally, the ascent stage was cast off, its purpose fulfilled, and entered a decaying orbit until finally it crashed somewhere on the Moon.
Each successful landing included one or more Extra Vehicular Activity (EVAs) during which both Astronauts walked on the Moon. Apollo 11 had just one (make the history, proof of concept), Apollo 12 and Apollo 14 each had two (a shorter, ceremonial/experiment setup walk, and a later exploratory walk), and Apollo 15, 16 and 17 each had three walks (set up the lunar rover and experiments, use the Rover to explore in three different directions and cover much more ground). A given mission's EVAs were simply referred to individually as EVA-1, EVA-2 or EVA-3 as needed. Since two men walked in each case, you can count up 2(1+2+2+3+3+3) = 28 individual instances or episodes of a person walking around on the Moon. See the chart in
>>11024882 for details (which includes all the other EVAs of the Apollo program).
An excellent quick animation on the entire flight profile is given from 30:22 - 32:52 below. If you pay close attention you can see that there's really ten major components which detach (or re-dock in a few cases) over the course of a mission.
https://www.youtube.com/watch?v=9GVpoSrqMMg 
