Shear strength testing measures a material's ability to resist shear forces, which are forces that cause layers of the material to slide past each other. This testing is crucial in fields like civil engineering and materials science, where understanding how materials behave under stress is essential for safety and design. The test typically involves applying a controlled load to a sample until it fails. Common methods include the direct shear test and triaxial shear test, each providing valuable data on the material's properties. Results help engineers select appropriate materials for construction and ensure structures can withstand applied forces.