Young's Modulus is a measure of a material's stiffness, defining the relationship between stress (force per unit area) and strain (deformation in response to stress) within the linear elasticity region of a material. It is calculated as the ratio of tensile stress to tensile strain and is expressed in units of Pascal (Pa). In CAE, understanding Young's Modulus is crucial because it helps engineers predict how materials will behave under various loads, ensuring that designs are both safe and efficient.