Why does the Moon change shape?

The Moon is lit by the Sun
and doesn’t give any light of its own.
However the Sun only lights half of the Moon,
Leaving the other half dark and invisible.
We can only see one face or side of the Moon from Earth,
Because we see this face from different angles
During the 29 1/2 days the Moon takes to orbit Earth.
Sometimes the Sun lights all of the face of the Moon that we see.
At other times only part is lit.