Drawing a Burr
When you're first sharpening a blade, successfully drawing a burr from each side of the knife is the most important step. It is very difficult to know for certain without the presense of a burr if the bevels on each side of the blade actually extend to the edge. If the bevels do not extend all the way to the edge, the edge of the knife will be blunt and the knife will not be sharp.
A burr is defined as (From Wikipedia) 'In engineering, a burr refers to the raised edge on a metal part. It may be present in the form of a fine wire on the edge of a freshly sharpened tool or as a raised portion on a surface, after being struck a blow from an equally hard, or heavy object.' A burr, also called a wire edge, is created as a result of sharpening metal. The burr forms on the edge of the knife where the planes of the bevels (or, in the case of one-sided knives or chisels, the plane of one face and the bevel) intersect. The diagram below shows the burr projecting from the edge of the knife:
The next diagram shows the formation of a burr in greater detail.