The visible shape of the Moon changes daily due to its orbital motion around the Earth and the changing angle of sunlight reflecting off its surface. This cycle of changes is called the lunar phases.

Here's a breakdown of the major phases:

* New Moon: The Moon is not visible as it's between the Earth and the Sun, so the sunlit side faces away from us.

* Waxing Crescent: A sliver of the Moon's illuminated side becomes visible, growing larger each night.

* First Quarter: Half the Moon appears illuminated, resembling a "D" shape.

* Waxing Gibbous: More than half the Moon appears illuminated, becoming more rounded.

* Full Moon: The entire face of the Moon is illuminated by the Sun, appearing round and bright.

* Waning Gibbous: The illuminated portion begins to decrease, becoming more rounded than a "D" shape.

* Last Quarter: Half the Moon appears illuminated again, resembling a "C" shape.

* Waning Crescent: The illuminated sliver continues to shrink until it disappears again.

The entire cycle from New Moon to New Moon takes approximately 29.5 days, which is called a synodic month.

Important Note: While we see a different shape of the Moon each day, the actual illuminated portion of the Moon remains constant. It's our perspective that changes due to the relative positions of the Sun, Earth, and Moon.