Hardness testing is described as the ability of a material to resist indentation. Hardness and strength are directly related. Therefore, if a material's hardness is known, we can estimate its material strength. There are numerous types of hardness measurements that can be taken depending on the type of material being examined. A few used for testing metals are Brinell, Vickers, Knoop and Rockwell A, B and C. There are other tests for determining the hardness in elastomers and fiberglass such as Durometer and Barcol.