The moon is large block of rock that does not change shape - it just looks as though it does. The shape we see in the sky today depends on how much of the moon's face is lit up. Sometimes we observe a thin #crescent, and at other times we see #half or three #quarters of the Moon, and then a fully lit face-- a #Full Moon.
#LUNAR_CYCLE: The view we have of the Moon changes acccording to the relative positions of the Sun, Earth, and Moon. A complete cycle of shapes, known as phases, takes 29.5 days.