This book covers detailed studies on nucleon-nucleus and nucleus-nucleus interactions at low energies within the framework of non-relativistic time-independent scattering theory. Instead of representing nuclear interaction by short-range local potential, physical processes like - , -12C, etc. which play major roles in stellar nucleosynthesis are described by nonlocal separable plus electromagnetic potential. In this regard, we provide brief mathematical approaches which give information on bound, scattering, and resonant states for a specific scattering problem. The nonlocal properties of two-body interactions can be better understood through the energy-dependent equivalent local potentials. Thus, different techniques for localization of nonlocal separable interactions to generate energy-dependent local potentials are emphasized at the beginning of this book. There are substantial usages of screened Coulomb potential in atomic and plasma sciences and is also regarded as the best representation of Coulomb one. Therefore, the various aspects of including screened/cut-off Coulomb potential in the scattering theory are deliberately discussed.