The textbook presents the physical foundations, goals, methods and means of tensometry. Types of characteristics and installation features of strain gauges, methods of thermal compensation, strain gauge techniques for measuring deformations are considered. Mechanical, optical, string strain gauges are described. Information on electrical tensometry means, wire and foil strain gauges, fiber-optic sensors, strain gauge transducers is provided. Peculiarities of strain-gauge testing rotating moving objects are revealed.