The Moon is the second-most prominent celestial body (next the Earth) featured in most Gundam series.
The Moon is the location of multiple Earth Federation Forces lunar cities, bases and/or factories used in the wars raging from the latter-quarter of the 1st U.C. century onward. Each city or base constructed on the Moon served as either a military factory or stronghold for a political faction in a war.
As it was deemed unsuitable for permanent human habitation, the Moon became a tourist attraction. During the Eve Wars, however, OZ constructed a Lunar Base that doubled as Mobile Doll manufacturing plant, which served to be critical in the latter-end of the Eve Wars. After the war, the Lunar Base became the resting place of the five Gundams.
One Lunar Base is located on the Moon, where the D.O.M.E. remains are kept, and serves as part of the Satellite System by sending the microwave beam to mobile suits equipped with the system. In AW 0015, however, the base is destroyed.
The Moon is the home of a futuristic utopian society of people, called the Moonrace, who have changed the barren landscape of the moon into a habitable paradise.
Like in the Universal Century timeline, the Moon houses many military bases used during the Alliance-PLANT Wars: only one lunar civilian city - Copernicus City - was ever built on the Moon.
The moon serves as the secret location of Veda, known as the Moon Terminal, along with the pod of Aeolia Schenberg. It was transferred to the mothership Celestial Being by Ribbons Almark after the terminal was discovered by both him and Alejandro Corner. The mothership Celestial Being holds its orbital position on the dark side of the moon at Lagrange 2.
The Moon is severely damaged from unknown causes during the Calamity War. Therefore, it's current appearance on every planet is similar to it's "New Moon".