Force and displacement measurements obtained from instrumented indentation experiments are interpreted using elastic contact models, even when the contact causes plastic deformation. Elastic contact models specify the ideal relationship between force, displacement, and elastic properties. Such models are explained in this presentation. Ian Sneddon’s elastic contact model is given special attention due to its generality, and the models of Hertz and Love are shown to be special cases of Sneddon’s model. Many examples are provided which show how to apply Sneddon’s model to specific geometries of contacting bodies.