Wüsthof honing steels, for daily maintenance of your knife

Every knife becomes (slowly) blunt after first use and must be sharpened again in time. By sharpening the knife regularly you can ensure a major sharpening session is delayed as long as possible.

You can do that with a honing steel (or whet steel). That is a steel with vertical ribs. You sharpen the knife by moving it a few times along the steel, which has to be longer than the knife. It must also be made of harder steel than the knife. VG10 for example, a steel which is often used for high quality kitchen knives, is too hard for a honing steel. By using this you don't do a favour to your knife or honing steel.

Honing steel or sharpening steel?

A honing steel removes any burrs off the cutting edge. Burrs are the first indication of a blunt knife. They are difficult to see at first. When burrs become larger you can see a glittering on the edge. A honing steel removes the rougher burrs and lifts the small burrs. That improves your knife edge. 

A honing steel only removes burrs, and no material from the knife. The knife thus still becomes round and blunt on the edge. A sharpening steel, diamond or ceramic, does sharpen the edge. They remove a layer of steel from your knife which shapes the cutting edge of the knife back into a V-shape. A diamond or ceramic sharpening steel is also quite a lot harder, which means you can actually sharpen any knife on it.