Simulation and Identification of Fractional Differential Equations (FDEs) and Systems (FDSs). The Fractional Integrator -- Frequency Approach to the Synthesis of the Fractional Integrator -- Comparison of Two Simulation Techniques -- Fractional Modeling of the Diffusive Interface -- Modeling of Physical Systems with Fractional Models: an Illustrative Example -- The Infinite State Approach. The Distributed Model of the Fractional Integrator -- Modeling of FDEs and FDSs -- Fractional Differentiation -- Analytical Expressions of FDS Transients -- Infinite State and Fractional Differentiation of Functions.