The moon (or Luna) is the Earth's only natural satellite and was formed 4.6 billion years ago around some 30-50 million years after the formation of the solar system. The Moon is in synchronous rotation with Earth meaning the same side is always facing the Earth. The first unmanned mission to the moon was in 1959 by the Soviet Lunar Program with the first manned landing being Apollo 11 in 1969.
Because Earth is moving in its orbit around the Sun at the same time, it takes slightly longer for the Moon to show the same phase to Earth, which is about 29.5 days