Unconventional natural gas resources are very important for ensuring energy security. It is a concern that conventional natural gas resources will be unable to meet growing supply requirements. This concern has prompted a scramble to secure long-term natural gas supplies. In a high oil and gas price environment, unconventional resources are viewed as important and economically attractive components of future natural gas supplies. Shale gas is natural gas produced from shale formations. Gas shales are organic-rich shale formations. Shale gas is a dry gas composed of methane. Various factors which have contributed to its rapid development are mainly advancements in horizontal drilling, hydraulic fracturing, and, perhaps most importantly, the rapid increase in natural gas prices in the last several years as a result of significant variation in supply and demand. India has a high potential for shale reserves. According to the available data, a comprehensive shale gas pilot project carried out in the Damodar Valley Basin has made an initial gasin- place estimate of 300 to 2,100 trillion cubic feet (TCF) in Indian shale gas basins, which is around 300 times higher than the Krishna Godavari Dhirubhai 6 (KG-D6) basin, by far the largest gas field in the country. In this paper, a brief review of shale gas reserves across the world and their government policies has been explained.