Electrochemistry plays a paramount role in both science and manufacturing, in addition to offering promising solutions for the conversion and storage of sustainable energy to protect the environment. To promote the further development of electrochemical processes, a more detailed description and better fundamental understanding are required. This calls for deep insights into the structure and dynamics of electrode–electrolyte interfaces at the atomic level, taking various external working conditions into account. By virtue of the evolution of modern chemistry, numerical simulations have been able to capture the complexity of these processes with increasing success, including consideration of the presence of the electrical double layer, explicit electrode–solvent interfaces, and the applied potential. This chapter highlights the status of current theoretical studies, demonstrating the availability of well-defined models and more accurate methods. Using selected examples, the gap between experiments and current theoretical work considering the complex operating environment of electrochemical processes is discussed. We believe that the development of more reliable modeling approaches and the application of multiscale simulations are crucial for further advancing the understanding of electrochemical processes.