Question

what is mean by tectonic plates ?

Answer 1

a theory in geology: the lithosphere of the earth is divided into a small number of plates which float on and travel independently over the mantle and much of the earth's seismic activity occurs at the boundaries of these plates.

Answer 2

Tectonic plates  is a scientific theory describing the large-scale motion of seven large plates and the movements of a larger number of smaller plates of the Earth's lithosphere.