It is well known that the critical field, -temperature and -current of Nb3Sn superconductors are very sensitive to deformations. In 1994 a new, three-dimensional (3D) model was presented, which accurately describes the behavior of the critical parameters with respect to strain, the so-called deviatoric strain description. In the following years an extensive number of Nb3Sn samples have been investigated, which resulted in a revised, unifying scaling relation for the critical current in Nb3Sn conductors as a function of field, temperature and strain, which included the 3D deformation model. Application of this scaling relation to all available data has confirmed the validity of the deviatoric strain description for various types of Nb3Sn conductors investigated in many experiments. A detailed explanatory review of the deviatoric strain description is presented and an update is provided on the latest results.