Plasticity is the property of a body by virtue of which it remains in its deformed shape and size even after the forces are removed. The plastic deformation in a body is produced under certain load conditions and can be studied using the stress and strain curve. The point at which the body ceases to be elastic and begins to deform plastically is known as the yield point. Permanent deformation of the body occurs once the yield point is passed. During plastic deformation, atoms of the body are permanently displaced from the original lattice site and retain the new site even after the external forces have been removed. The point on the stress-strain curve that represents the maximum stress that the body can endure before breaking apart is known as the ultimate stress point, and the point beyond which the body breaks or ruptures is called the fracture point.