There are as many different sharpening tools. Most of them work to one degree or another:

 

Steels: These are the long metal rods that come with many knife set and is the traditional tool that chefs use to sharpen their knives.

 

Honing: This is the term used for aligning or straightening the knife's edge between sharpening sessions. This term and sharpening method is not as effective as it once was when knives where made out of more simple, softer carbon steels. The edges of those knives tended to bend under cutting pressure and would straighten with the use of a steel and the honing steel removed some metal from the blade or sharpened it. The traditional steel will maintain a knife's edge for a while but will do nothing to sharpen even a slightly dull knife. Some people like to use it to polish the edge after sharpening by another method.

 

Diamond or Ceramic Steel: Though shaped like the traditional honing steel, these tools are sharpeners not hones. Because ceramic and diamonds are much harder than steel, when you use these tools they remove metal from the knife's edge or sharpen it.

 

Sharpening Stones: This is the oldest and the most traditional method of sharpening and is made out of different materials. Some sharpen faster than others. If you use this method, you will want to have 2-4 different coarsenesses, or grits, of stone. The coarsest should be used on very dull knives or to grind out chips in the blade. The finest grit stone is to polish the edge of the blade. As with all sharpening methods, it is best to keep the knife sharp with frequent use of the finer stones and avoid using the coarser stones except when absolutely necessary. This will insure your knife is always in optimal working condition and prolong its working life by removing less metal from the blade.

 

Sharpening Serrated Knives: You can do a good job of restoring a serrated knife's edge by sharpening it on a diamond or ceramic steel. This technique will only work on a knife made out of high quality steel. Cheap knives are often made with serration and inferior quality steel. These knives will not sharpen well!

 

Serration on knives is almost always ground on only one side of the knife.

 

Some people like to get a very small round file and sharpen each serration individually. This is a very time consuming process.