Moons are natural satellites that orbit planets, and they come in various sizes and compositions. The most famous moon is Earth's Moon, which plays a crucial role in influencing tides and stabilizing the planet's axial tilt. Other notable moons include Jupiter's Ganymede, the largest moon in the solar system, and Saturn's Titan, known for its thick atmosphere and lakes of liquid methane. Moons can be rocky, icy, or gaseous, and they often have unique geological features. Some moons, like Europa, are believed to harbor subsurface oceans, raising the possibility of extraterrestrial life. The study of moons helps scientists understand the formation and evolution of planetary systems.