The Moon’s gravity is too weak to retain an atmosphere. Gases escape into space. There is a thin exosphere instead. It contains atoms kicked up by impacts. Temperatures swing wildly. Day and night differ drastically.
This matters because conditions are extreme. Equipment must handle harsh environments. Human survival requires protection.
It also preserves history. Without air or weather, footprints last millions of years. The past stays intact.
Astronaut footprints on the Moon may last over 100 million years.
[NASA, nasa.gov]