This paper reviews four critical mechanisms for successful applications of hydraulic fracturing that have emerged or grown in importance over the past 2 decades. These critical issues are managing height growth, decreasing near-wellbore tortuosity, predicting and engineering network versus localized growth geometry, and promoting simultaneous growth of multiple hydraulic fractures. Building on the foundation of decades of research relevant to each area but with an emphasis on advances within the past 20 years, the review presents available field evidence, laboratory data, and modeling insights that comprise the current state of knowledge. Fluid viscosity, injection rate, and in situ stresses are shown to appear as controlling parameters across all of these issues. The past contributions and limitations on future developments point to a future in which advances are enabled by a combination of fully coupled 3D simulations, advanced laboratory experiments, vastly expanded characterization capabilities, and order of magnitude improvements in monitoring resolution.