The Moon is Earth's only natural satellite. It orbits around Earth at an average distance of 384,399 kilometres, about 30 times Earth's diameter. Its orbital period and its rotation period are synchronized at 29.5 days by the pull of Earth's gravity. This makes the Moon tidally locked to Earth, always facing it with the same side. The Moon's gravitational pull produces tidal forces on Earth which are the main driver of Earth's tides.
In geophysical terms, the Moon is a planetary-mass object or satellite planet. Its mass is 1.2% that of the Earth, and its diameter is 3,474 km, roughly one-quarter of Earth's. Within the Solar System, it is the largest and most massive satellite in relation to its parent planet. From Wikipedia
