The most significant development in upstream oil and gas in the last decade has been the surge in development of unconventional resources, especially shale oil and gas. Hydraulic fracturing (the most important stimulation technique in these reservoirs) has evolved rapidly, mostly through operational trial and error. The primary challenge to economically optimal development of unconventional resources is the current inability to reliably predict production from individual wells, and hence to make stimulation design decisions for the specific well or area. One of the largest impediments to such predictions is the limited knowledge of the pre-existing fracture network and its impact on the success of stimulation treatments. Microseismic data, and the rigorous inclusion of the DFN into hydraulic fracture design and simulation tools is critical to removing this impediment.