A razor blade and an ax both have a cutting edge and both could be made of equally hard material. However, only one could cut a human hair and only one could cut a tree trunk. The difference is with the edge. One is thin, light, and fine, the other one is thick, heavy, and robust. The edges of precision hand cutting tools are robust or fine, or a compromise between robust and fine. The following slides will describe the three cutting edge styles in more detail.