[header] How to use a knife sharpener [title] Examine the knife sharpener. [step] There are multiple types of manual knife sharpeners. Some only have one slot, while others may have two or three. 
[substeps] Each slot should have two steel, ceramic, or diamond-coated disks on either side, and these disks are what sharpen the blade of the knife. Simple knife sharpeners only have on sharpening slot, but others have two or three.