2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/62464A solution to the more than 300-years old problem of geometric and physical interpretation of fractional integration and differentiation (i.e., integration and differentiation of an arbitrary real order) is suggested for the Riemann-Liouville fractional integration and differentiation, the Caputo fractional differentiation, the Riesz potential, and the Feller potential. It is also generalized for giving a new geometric and physical interpretation of more general convolution integrals of the Volterra type. Besides this, a new physical interpretation is suggested for the Stieltjes integral.18 pages, 7 figures, 1 tableClassical Analysis and ODEsMathematical Physics26A33 (Primary) 26A42, 83C99, 44A35, 45D05 (Secondary)text