The Solar System contains at least 176 moons, which orbit six of the eight planets. Mercury and Venus are the only two planets which do not have a moon.
Of the terrestrial planets, Earth has one moon, which we call the Moon; and Mars has two small moons, called Phobos and Deimos.
Once we move into the outer Solar System, the large gas giant planets have many moons. Jupiter is thought to have the most moons with a current total of 67, of which 4 (Io, Europa, Ganymede, Callisto) are comparable in size to Earth's moon. Next comes Saturn with 62 moons including Titan, a large moon with a thick atmosphere of Methane. Uranus and Neptune also have many moons with 27 and 13 respectively.
Some of the moons in the Solar System were created at the same time as their parent planets, while others may have formed separately, and then been captured when drifting to close to one of the planets.
The above animations show what some of the future missions to the moons of the Solar System, and other interesting places, might look like.