Fossil fuels play a dominant role in global energy system. With an ease to develop and extract conventional resources fast depleting, unconventional fossil fuel resources shall play an important role in the future. With advances in technology, like horizontal drilling and hydrofracturing, unconventional resources like shale gas and coal seam gas are increasingly playing a bigger role in the present-day footprint of fossil fuels. It is therefore imperative to understand their settings, occurrence, and global distribution of these unconventional energy resources. The present chapter is an attempt to present an overview of the various fossil field resources available on earth, their geographical distribution and resource potential, their potential prospects, and technological challenges facing their extraction and exploitation.