A wide variety of raw materials and ancillary materials are used in industrial applications. Comprehensive knowledge of their material properties is an absolute prerequisite for using these raw materials for a defined application in technical environments. Hardness tests are a way to determine basic material properties such as hardness/ductility and strength of a material, such as steel. Hardness plays a critical role in the characterization and quality control of materials. The hardness of a steel provides information about its mechanical properties, wear resistance and suitability for specific applications. In this context, various hardness testing methods and scales have been developed to accurately determine and classify the hardness of steel. This article provides an overview of common hardness test methods, an overview of some of the heat treatment options for steel materials, the resulting Vickers hardness levels and their possible applications.