The mission of distribution system operators (DSOs) is to operate and manage distribution networks in a safe and secure manner. DSOs are also responsible for developing distribution grids to ensure the long-term ability of a system to deliver high-quality services to users and other stakeholders of the electric power system. Traditionally, DSOs have carried out their mission through adequate network operation and planning. However, the profound transformation of the energy system that is currently taking place worldwide creates new challenges for DSOs to carry out their responsibilities in a cost-efficient and secure manner. A significant number of renewable energy sources (RESs) are already connected, and more are expected in the future. Furthermore, the number of electric vehicles (EVs) and public charging stations will see a major increase in the coming years. These trends are coupled with an exponential technological evolution that enables decentralized energy sources to be connected at lower voltages and, at the same time, enables customers to interact with the market in response to grid conditions.