Flint knapping is a reduction process; flakes of stone are broken off of the of the original piece. Carl Doney of Michigan State University explains: knappers, both ancient and modern, generally begin knapping a piece of stone with direct percussion. Direct percussion is accomplished by directly striking the stone which is to be made into a projectile point, etc., with a tool, such as a hammerstone or antler billet to remove large flakes. The purpose of direct percussion is to thin the stone to the required thickness. Generally, the next step is pressure flaking. Pressure flaking is achieved by placing a pointed tool, such as an antler tine or copper-tipped pressure flaker, on the edge of the stone, and applying an inward pressure to the tool. This pressure will remove a small, thin flake from the stone. Pressure flaking shapes and refines the projectile point. The finished points can include notching, stemming, or fluting.
Also good for hunting aurochs.