Why does the Moon Wax And Wane ?

The Sun can shine on only one half or hemisphere of the Moon.As it orbits the Earth every month, our view of this half changes.
At New Moon this half of the Moon is turned away from the earth, and cannot be seen, while at Full it is turned towards us.The time as the moon grows from New to Full is called ‘waxing’. After Full, the Moon ‘wanes’ or shrinks to invisibility once more.