Effective hydraulic fracture stimulation is critical for shale development, and microseismic is the only technology able to map the growth of these hydraulic fracture networks. Since the advent of commercial mapping in the Barnett Shale in 2000, microseismic has been used to investigate hydraulic fracture treatments around the globe. Microseismic can be used to tune the stimulation to cover just the intended reservoir depth interval without fracturing out of zone, understand the primary fracture orientation to optimize the well orientation, define the optimum spacing between stages and detect unexpected fracture growth such as fault activation. More fundamentally, however, microseismic images of complex fracture networks have fundamentally changed the conceptual view of hydraulic fractures from simple, planar fractures to intersecting fracture networks in various directions. The recent development of complex fracture models, which implicitly simulate both the geomechanics and mass balance of the injected fluid volume, offer promise to estimate the effective propped volume of the fracture network. These geomechanical simulations also provide insight into not only where the rock is fracturing, but also allow interpretation of microseismic source deformation and mechanism attributes which provide further insight into how the fractures deform.