Stone tools are frequently the subject of archaeological analyses as they exhibit exceptional preservation and are often the most numerous artifact at early prehistoric sites. In some early sites, stone tools are the only sign of human activity. The category of stone tools not only contains finished tools, but also cores (large chunks of rock from which pieces are broken off to make tools) and flakes (material that is wasted when making a tool). One technique used to analyze stone tools is categorization. Categorization organizes observations into “a limited set of groupings that can be said to be alike in a defined way.” Categorization can either be achieved by: