A measure of the change in the size or shape of a body, referred to its original size or shape. “Linear Strain” is the change per unit length of a linear dimension. “True Strain” (or “natural strain”) is the natural logarithm of the ratio of the length at the moment of observation to the original gauge length. “Conventional strain” is the linear strain referred to the original gauge length. “Shearing strain” (or “shear strain”) is the change in angle (expressed in radians) between two lines originally at right angles. When the term strain is used alone it usually refers to the linear strain in the direction of the applied stress.