Question

what is tides? how they form?

Answer 1

Tides refer to the rise and fall of our oceans’ surfaces. It is caused by the attractive forces of the Moon and Sun’s gravitational fields as well as the centrifugal force due to the Earth’s spin. As the positions of these celestial bodies  change, so do the surfaces’ heights. For example, when the Sun and Moon are aligned with the Earth, water levels in ocean surfaces fronting them are pulled and subsequently rise.

Answer 2

Tides refer to the rise and fall of our oceans' surfaces. It is caused by the attractive forces of the Moon and Sun's gravitational fields as well as the centrifugal force due to the Earth's spin. As the positions of these celestial bodies change, so do the surfaces' heights.Tides are periodic rises and falls of large bodies of water. Tides are caused by the gravitational interaction between the Earth and the Moon. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. ... Isaac Newton was the first person to explain tides scientifically.