Why does the moon appear to wax grow larger and then wane or get smaller

When the moon is waxing it means that the sunlit fraction we can see from earth is getting larger. when it is wanning, the sunlit fraction is getting smaller and even as the phases of the moon change the total amount of sunlight the moon gets remains the same. half the moon is always in sunlight just as half the earth is always in sunlight. but because the period of rotation for the moon is the same as its period of revolution, on earth we always see the same side of the moon. If you lived on the far side of the moon, you would see the sun for half of each lunar day, but you would never see the earth.