This TLP concerns mechanical testing in the form of uniaxial compressive or tensile loading, and also indentation procedures (both hardness measurement and more advanced techniques). Tested materials are treated as isotropic continua. The focus is on plastic deformation and its representation by constitutive laws. No attempt is made to relate the plasticity characteristics to the micro-mechanisms responsible for them. The main aim is to provide both practical advice about how to carry out these tests and insights into the information provided by them.