Abstract—The ever-increasing demand for electricity has posed reliability, security, economic and environmental challenges in front of the current electricity power system. A smart grid concept is a key solution to these issues because it uses digital technology to revolutionize the conventional electricity power system. The electricity power system contains three sections, namely generation, transmission and distribution. This paper discusses the important aspects and concepts of the reliability in the distribution section. Since reliability in Distribution Systems (DSs) has always been a major concern for utility providers, we have surveyed existing reliability methodologies and recent research works to improve reliability and calculate reliability indices. The integration of renewable based Distribution Generation (DG) and Energy Storage Systems (ESSs) into grid solutions is also considered in this paper as they can provide reliable power to consumers and reduce electricity losses, reliance on centralized plants as well as the environmental impacts. Furthermore, this paper highlights future challenges and directions in smart grid communication networks from a reliability perspective.