The earth is a planet, which moves steadily around the sun in a nearly circular orbit. Its orbit around the sun is called the revolution of the earth. When the earth revolves around the sun, it also rotates. The revolution of the earth around the sun is one year, and the rotation of the earth is one day.
The moon is also a planet, called the moon. The moon is a satellite and the only natural satellite on the earth. It orbits the earth stably in a nearly circular orbit, which is called the revolution of the moon. When the moon revolves around the earth, it also rotates. It takes a month for the moon to go around the earth. Because of the tidal locking effect of the earth on the moon, the period of the moon's revolution is the same as that of its rotation, so on the earth, we can only see the same side of the moon, but not the other side. When the moon revolves around the earth, due to the change of its relative position with the earth, from the earth's point of view, the side of the moon illuminated by the sun faces the earth at different angles, which makes the moon show different light and dark changes in a month's time, called the moon phase.
The earth and the moon make up the earth-moon system. Both the earth and the moon revolve around the sun.