Energetic charged particles (Cosmic rays) are one of the main contributors to the nonthermal energies in the universe. Although diffusive shock acceleration (DSA) is the promising mechanism for particle acceleration at shocks, whether the processes that promote particles to DSA act similarly for electrons and protons/ions is still not well understood. In this talk, I will present our ongoing efforts using ab-initio kinetic simulations to solve the problem and discuss under which conditions electrons and protons participate in the DSA. I will also outline how the energetic particles modify the initial magnetic field by producing different plasma instabilities. Finally, I will discuss the implications of these results to astrophysical sources from planet's bow shocks to galaxy clusters.