Moons are celestial bodies that orbit a star or a planet. While most moons we know orbit planets, there are also "planetary-mass objects" that orbit stars directly, without orbiting a planet. These are sometimes referred to as "rogue planets" or "free-floating planets."

Examples:

* Pluto's moon Charon is so massive that it's considered a "dwarf planet" in its own right. It orbits Pluto in a way that's more like a mutual orbit than a typical moon orbiting a planet.

* Some astronomers argue that Earth's moon should be classified as a "dwarf planet" due to its size and influence on the Earth.

Therefore, while most moons we know orbit planets, there are exceptions, and the definition of a "moon" can be somewhat flexible.