In response to someone's question "Earth is divided in how many tectonic plates ?"
The image shows the boundaries of the tectonic plates in the Earth's crust, responsible for earthquakes and volcanoes. Geologically, Indian plate is quite active since formation of the earth hence the largest peaks are in the Himalayas and Hindukush regions. Stresses releasing up on the surface.
If there was no plate tectonics there would be no life. We would be like Mars; our atmosphere would have flown away. Without a strong magnetic shield to protect its atmosphere, life cannot exist. Earth maintains a sufficiently strong magnetic field because of the tectonic plate action.
No tectonic action, no life, it is magnetic shield that holds the thin shield of our planet's atmosphere together. The Earth's magnetic field is driven by a reactor deep in the Earth's outer core, that is driven in turn by convection currents of our planet's interior. The convection inside a planet over periods of billions of years is maintained through basic science as the interior of the Earth is very hot, the slow decay of radioactive elements in the interior earth planet sheds heat through its crust resulting in surface layers of our planet's interior which are cooler than those near the core.
Convection needs such a large temperature difference; convection currents in the Earth's mantle form as the part of the mantle just beneath the crust is far cooler than that next to the core.
If the Earth didn't have plate tectonics, the upper layers of the mantle would not be able to cope with a warm upper mantle, the temperature difference between that region and the Earth's deep interior would be smaller, and convection would eventually cease. And without that convection, the Earth's inner core reactor would die, and its magnetic field would as a result disappear.
This is precisely what happened to Mars. At first, the red planet may well have been sufficiently hot inside for a certain degree of tectonic activity to occur. Certainly, the crust of Mars bears evidence of an ancient magnetic field, frozen into the rocks.