In elastic field, and elastic modulus, is a quantity that measures an object or substance’s resistance to being deformed elastically.

**Young’s modulus** (E) describes tensile elasticity, or the tendency of an object to deform along an axis when opposing forces are applied along that axis; it is defined as the ratio of tensile stress to tensile strain. It is often referred to simply as the elastic modulus.

The **shear modulus** ( or µ) describes an object’s tendency to shear (the deformation of shape at constant volume) when acted upon by opposing forces; it is defined as shear stress over shear strain. The shear modulus is part of the derivation of viscosity.

The **bulk modulus** (K) describes volumetric elasticity, or the tendency of an object to deform in all directions when uniformly loaded in all directions; it is defined as volumetric stress over volumetric strain. The bulk modulus is an extension of Young’s modulus to three dimensions.