Armstrong famously called the historic achievement a "giant leap for mankind." Buzz Aldrin followed him onto the lunar surface, while their crewmate Michael Collins stayed on the main spacecraft in orbit around the moon.
After the three astronauts returned to Earth, they were quarantined for 21 days to make sure they did not bring home any lunar contagions. Armstrong turned 39 during the confinement.
Until the Apollo 11 mission, Russian cosmonauts had been ahead of the US at almost every turn in the Cold War space race. At the time, many Americans did not believe spending $24.5 billion on the Apollo missions was worth it, and some people protested NASA's eight-year effort to land on the moon.
Armstrong, meanwhile, had a few near-death experiences in the years leading up to the moon landing. In March 1966, he and co-pilot David Scott were almost lost in space during the Gemini 8 mission. This was the first attempt to dock one spacecraft with another while in orbit, an essential step in a moon landing. But soon after takeoff, a thruster malfunctioned, which sent Armstrong and Scott spinning out of control. Luckily, they found a way to regain control of the spacecraft by powering thrusters.