An end grain board is comprised of the ends of many individual pieces of hardwood placed face up. This configuration is generally preferred because the knife blade slides between the ends of the individual fibers in the wood when cutting, separating them slightly, instead of cutting across the fibers, as happens with a edge grain or face grain surfaces. When the knife is removed, the fibers close in a self-healing effect. The result is that your knives stay sharper longer, the blade edges last longer, as does the surface of the cutting board. Also, the greater tolerance for the chopping motion in end grain boards makes knife work more nuanced and satisfying.