Dear Student,
Newton's law of gravitation states that particles attract each other with a force. This force between the particles is proportional to the product of their masses and inversely proportional to the distance between them.
Tides are caused by the tidal forces created by the differential gravitational forces exerted by the moon on the earth and residual forces which act on the water present on the earth. The rotation of the earth is also responsible for the tides.
Regards