CBSE Class 9 Answered

Tides are created because the Earth and the moon are attracted to each other, just like magnets are attracted to each other. The moon tries to pull at anything on the Earth to bring it closer. But, the Earth is able to hold onto everything(including non living living objects and water stored in a glass) except the water in oceans and seas. Since the water is always moving, the Earth cannot hold onto it, and the moon is able to pull at it.

The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since the Earth is also being pulled toward the moon (and away from the water on the far side).