A change in the shape of an object due to an applied force is known as deformation. Squeezing, twisting, squashing, or pulling the object apart are some examples of deformations. Let us consider a wooden plank of length L. When a force is applied on the top surface of the plank in a downward direction, the plank undergoes deformation. The magnitude of the applied force per unit area is called stress. The SI unit of stress is the pascal and is defined as the force of one newton exerted over a unit surface area of one meter squared. Stress can be categorized as tensile stress, compressive stress, volume stress, and shear stress. When the deforming force on an object results in an increase or a decrease in the object's length, it is termed as tensile or compressive stress, respectively. Whereas, if the volume of an object changes due to the deforming force, it is termed as volume stress. If the direction of the deforming force is parallel to the cross-sectional area, it is called shear stress.