In the twenty-first century the most critical and important issues with regards to the global climate change problem are Smart Grid (SG) and Renewable Energy (RE) technologies. The evolution of current centralized generation in the form of Distributed Generation (DG) and SG provides a great opportunity to eradicate several issues associated with energy efficiency, energy security, power quality and the drawback of aging power system infrastructures. In order to meet the rising electrical power demand, increase service quality and reduce pollution, the existing power grid infrastructure should be developed into a SG that has the flexibility to allow interconnection with the DG. However, integrating DG to power systems causes several technical issues, especially system stability. This book, therefore, provides a review state of the art DG and SG as well as discusses the impacts of DG on SG. This research will contribute to the knowledge in Distributed Generation and Smart Grid areas since it has become a leading concern in the field of power systems, in particular with its development in industrial nations worldwide.