The resistance of a material to deformation is called stiffness. It is a fundamental property that reflects how much a material resists changes in shape or size when subjected to force. Stiffness is crucial in engineering and materials science, as it affects how structures respond to loads. Materials with high stiffness tend to maintain their shape under stress, while those with low stiffness may bend or stretch easily. The measurement of stiffness is used in various applications, from construction to automotive design, ensuring that materials can support necessary loads without excessive deformation.