The Modulus of Elasticity is a measure of a material's stiffness or rigidity. It quantifies how much a material will deform under stress, specifically how much it stretches or compresses when a force is applied. A higher modulus indicates that the material is stiffer and will deform less under the same load, while a lower modulus suggests greater flexibility. This property is crucial in engineering and construction, as it helps determine how materials like steel, concrete, and wood will behave under various loads. Understanding the modulus of elasticity allows engineers to select appropriate materials for structures, ensuring safety and performance.