With the increased natural gas prices and advancement in the horizontal drilling and hydraulic fracturing technology, there is a high interest in shale gas reservoirs in the world and in Turkey. However, gas production from shale gas reservoirs is quite different than conventional gas reservoirs because permeability in shale gas reservoirs is very low and production mechanism is different due to adsorbed gas and free gas together in these reservoirs. The aim of study is to clarify shale gas reservoirs in terms of the world and Turkey's shale gas potential, gas production mechanism, and current techniques applied.