Learning Goal:To develop an understanding of ductility (or brittleness) and how it can be determined by the behavior exhibited on a stress vs. strain plot. Materials can be either ductile or brittle depending on their stress-strain behavior. Generally, ductile materials experience large strains before failure, whereas brittle materials experience relatively little strain before failure. How ductile (or brittle) a material is provides engineers insight into what different materials may be best suited for certain applications.