This is a self-contained exploration of the theoretical background of one of the most widespread activities in hydrocarbon wells, that of hydraulic fracturing. The authors provide readers with descriptions of the basic phenomena, including linear elasticity, stresses, fracture geometry and rheology. The diverse concepts of mechanics are integrated into a coherent description of hydraulic fracture propagation. Each of the chapters in the book are cross-referenced, with emphasis on the connections between the various phenomena and numerical examples.