The grid method is the oldest and simplest method for strain measurement. It is an experimental technique in which a grid is applied to the surface of a specimen. A grid is defined as one or more lines, dots or other shapes assembled in regular or irregular patterns. A comparison of the deformed grid on the specimen, undergoing a general state of loading, to that of a reference state yields the state of deformation. The emphasis in this paper is on reviewing experimental techniques emphasizing optical, non-contact, non-interfering and automated means of making deformation measurements using the grid method. Thus, the objectives of this paper are: to briefly review the basic principles and applications of the grid method in transparent and opaque solids, to describe the state-of-the-art, and, to point in the direction of its future evolution.