Faces of Moon
The Moon shines because it is illuminated by the Sun. It orbits around the Earth, whilst at the same time it accompanies Earth around the Sun. Due to which, the position of the Moon in respect to the Earth goes through different phases.
The Moon is full when it is directly opposite to the Sun. It looks like a scythe when it receives light from the Sun sideways. It becomes almost invisible when the Sun is behind it, as at this position the Sun only illuminates the sides of the Moon which we never see.
The phases during which the Moon is almost invisible are called the New Moon Between the New Moon and the Full Moon there is the Crescent Moon. Between the Full Moon and the New Moon is the Waning Moon.
The lunar phase or phase of the moon is the shape of the illuminated portion of the Moon as seen by an observer on Earth. The lunar phases change cyclically as the Moon orbits the Earth, according to the changing positions of the Moon and Sun relative to the Earth.
The cycle of lunar phases is called a lunar month and lasts about 29 and a half days.
Always same side of the Moon
The moon orbits in an anticlockwise movement around the Earth, taking 27 days and 3 hours. Within the same interval of time it also completes a complete rotation on its own axis. That is why it is always the same side towards the Earth, making it seem that the Moon does not move.