The importance of seafloor spreading to the theory of plate tectonics is best captured by the statement:
"Where new crust is created as plates move and pull apart."
Seafloor spreading explains how tectonic plates are created at mid-ocean ridges, where magma rises from the mantle to form new oceanic crust, resulting in the movement of the plates away from the ridge. This process is fundamental to understanding plate tectonics and the dynamic nature of Earth's lithosphere.