Here's a breakdown:

* The moon doesn't actually change shape. It's a sphere, just like the Earth.

* The phases are caused by the changing angle at which we see the sunlit portion of the moon. As the moon orbits the Earth, the amount of sunlight reflecting off its surface that we see changes.

Think of it like this: imagine holding a ball in your hand and shining a flashlight on it. Depending on the angle of the flashlight, you'll see different amounts of the illuminated surface of the ball.

Here are the main lunar phases:

* New Moon: The moon is between the Earth and the sun, so we can't see it.

* Waxing Crescent: A sliver of the moon becomes visible, growing larger each night.

* First Quarter: Half the moon is illuminated, resembling a quarter circle.

* Waxing Gibbous: More than half the moon is visible, growing larger each night.

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

* Waning Gibbous: The illuminated portion of the moon begins to decrease, shrinking each night.

* Last Quarter: Half the moon is illuminated again, but the lit side is on the opposite side from the First Quarter.

* Waning Crescent: The moon continues to shrink until it disappears again, becoming a New Moon.

This cycle of phases repeats approximately every 29.5 days.