There are three reputable forms of proof that moon landings occurred: photographs, rock samples and firsthand accounts. For many people, the lack of dissension from the Soviet Union is evidence in itself.
An abundance of photographs exist confirming the occurrence of a moon landing. While conspiracy theorists refute the legitimacy of such photos, the arguments are easily disproved. Some people claim that the shadows and light visible in the pictures is confirmation that the photographs were staged. However, these claims are rooted in an understanding of how light behaves in the Earth's atmosphere. Absent an atmosphere, refraction and reflection perform differently on the Moon, and a variety of factors, such as reflective paneling on the Lunar Module, greatly impacted the lighting.
Apollo astronauts delivered 841 pounds of lunar rocks to the Earth. These rocks lack the clay minerals common to Earth rocks, and are nearly void of any water trapped in their crystal composition. They are sprinkled with small craters from meteoroid impacts as well. Historical preservation sites, such as the Smithsonian, allow members of the public to examine and hold the lightweight rocks brought back from the moon.
Astronauts repeatedly confirm that they have landed on the Moon. Approximately 400,000 people were involved in sending astronauts to the Moon. Of these people, not a single one has publicly challenged the notion that humans landed on the Moon. A hoax of this magnitude would entail millions of dollars and is statistically impossible to cover up. The Soviet Union, who would have gained tremendously from proving the landing was a hoax, has not presented one piece of evidence to do so.