The fundamental processes and the mechanisms of low energy positron interaction with solid state surfaces are analyzed. The processes of positron retardation, inelastic scattering and inter-action with the particles and quasiparticles of the surface area of the solid state, and also the orocesses of the secondary particle excitation and positronium atom formation near the surface are considered and classified according to the energies. The theoretical concepts of elastic and nelastic scattering are developed; new experimental data are obtained on the backscattering of ow energy positrons for the diagnostics of the solid state surface properties.