Abstract: Smart grid system is a convoluted system in order to provide profound changes in the current grid system. This is fully automated grid utilizes latest information, communication techniques and internet which is truly interconnected and highly open to cyber attacks. Any attack in one location easily propagates through the network and can have immediate impact over wide area network. Without ample security implementation, a smart grid leads to serious outcome such as instability of the grid, malfunctioning of devices, theft in user information and fraud in consumer’s energy consumption data. This work briefs the smart grid technologies, key factors, types of attacks and mainly the authentication schemes used to minimize the attacks.