Honing is different from sharpening because it does not remove metal from the knife in order to form an edge, but instead realigns the edge so it can function at its maximum sharpness.

A knife’s edge consists of microscopic “teeth” that give the edge its sharpness and honing is the process of straightening the “teeth” that have become bent or curled during use.

A honing rod made of steel or ceramic can be run against the full knife edge according to the angle it has been sharpened to which will realign the steel “teeth” and restore the knife’s working edge.

Here is a link to a video of Michelin starred Chef Thomas Keller explaining how to properly hone a knife: