Hardness testing is a method used to determine the resistance of a material to deformation, particularly permanent deformation, indentation, or scratching. This testing is crucial in various industries, including manufacturing and construction, as it helps in selecting the right materials for specific applications. There are several techniques for hardness testing, such as the Brinell, Rockwell, and Vickers methods. Each method uses different scales and indenters to measure hardness, providing valuable information about a material's durability and performance under stress.