It sounds like you're asking about the different phases of the moon! The moon doesn't have "bits" that are missing, but it *appears* to change shape because of the way sunlight reflects off of it.

Here's the breakdown:

* The moon doesn't produce its own light. It reflects sunlight.

* The moon's orbit around Earth takes about a month. As it orbits, the angle at which the sun shines on the moon changes.

* We see different amounts of the illuminated side of the moon throughout the month, creating the phases.

So, while the moon might *appear* to be missing "bits" when it's not full, it's actually just showing us different amounts of its illuminated side.

Hope this helps!