The phases of the Moon
The Moon makes no light of its own. We see the part lit by the Sun, and that part changes as the Moon orbits Earth.
New moon
The Moon is between Earth and the Sun and is almost invisible.
Waxing crescent
A thin, growing sliver appears in the evening sky after sunset.
First quarter
Exactly half the disc is lit and the Moon keeps growing.
Waxing gibbous
More than half is lit as the Moon heads towards full.
Full moon
Earth is between the Sun and Moon and the whole disc is lit.
Waning gibbous
The light is shrinking, but more than half is still lit.
Last quarter
Half is lit again, this time the opposite side.
Waning crescent
A shrinking crescent, best seen in the early morning.