What Is A Canon EF-S Lens?
EF-S lenses are designed specifically for Canon APS-C sensor cameras. It is not possible to mount an EF-S lens on an APS-H, or a full frame camera.
Since crop sensor cameras do not make use of the full width of full frame lenses, you end up carrying around a lot more lens than is really necessary! EF-S lenses are lighter and smaller, because they don’t need to cover such a large image circle.