Here's a breakdown:

* Crescent: A thin sliver of the moon, either waxing (growing larger) or waning (growing smaller).

* Gibbous: A more than half-illuminated moon, also either waxing or waning.

* Full Moon: The entire face of the moon is illuminated.

* New Moon: The moon is completely dark and invisible from Earth.

So, the moon goes through phases, and you see different shapes, not just crescents!