Key characteristics:
* Orbits another body: It's not independent, but rather revolves around a larger object.
* Natural: It wasn't placed there by humans or any other artificial means. It formed naturally through processes like accretion or capture.
* Not a star: It doesn't generate its own light, instead reflects light from its parent object.
* Wide range of sizes and compositions: Moons can be tiny (like the potato-shaped moon of Mars, Phobos) or massive (like Jupiter's moon, Ganymede, which is larger than the planet Mercury). They can be rocky, icy, or even have atmospheres.
Examples:
* Earth's moon is the most familiar example.
* Jupiter's moons: This planet has over 70 moons, some of which are quite large and interesting, like Io, Europa, and Ganymede.
* Saturn's rings: These are technically made up of countless small, icy moons, ranging in size from dust particles to boulders.
Important Note: Some objects, like Pluto's Charon, are so large and close to their parent object that they are sometimes considered a "binary system" instead of a planet and moon.
