The combination of the Savage surface energy and the Bowden and Tabor junction formation mechanisms of production of frictional energy is suggested. The physical description of the experiments is sufficiently simplified and represented by a stable state which envelopes the whole field of friction. This leads to a qualitative and satisfactory agreement with the observed results for the values of coefficients of friction between solid surfaces, between solid surfaces with thin liquid or solid soft metal films, for wear, and for the correlation between friction and wear. The coefficient of wear is defined analogously to the coefficient of friction.