The book presents in a clear, simple, straightforward, novel  and unified manner the most used methods of experimental mechanics of solids for the determination of displacements, strains and stresses. Emphasis is given on the principles of operation of the various methods, not in their applications to engineering problems. The book is divided into sixteen chapters which include strain gages, basic optics, geometric and interferometric moiré, optical methods (photoelasticity, interferometry, holography, caustics, speckle methods, digital image correlation),...