Energy plays a vital role in our life. In recent decades, managing demand and supply of energy and maintaining the balance has become more complicated due to some technical, financial and environmental factors like growing electricity demand, old infrastructure, volatile energy costs, and intermittent resources. Therefore, the energy dilemma must be tackled with comprehensive and practical solutions. Moving toward demand-side management (DSM) is one of the most recent approaches, which can help electrical utilities and governors to achieve their goals. This transition has been accelerated by inventing new devices, deregulating electricity markets, and empowering end-users to be aware of electricity price via the smart meters. The smart home concept is one of the critical components to implement DSM in power distribution networks, which includes different types of DERs such as PV, ESS, Electric Vehicle (EV), and controllable appliances. In this dissertation, a novel Smart Home Management System (SHMS) is presented to deploy smart control strategies to maximize the beneficial effects of DERs and household appliances. Besides, a mathematical model of residential energy management considering electricity bill, transformer asset management, and energy loss is introduced. This dissertation also develops an optimization approach of DR aggregator to alleviate transmission congestion in the presence of DR and DERs. In the third part, the impact of DR on reliability improvement and the efficiency of microgrids is studied.