Book excerpt: Porous media are ubiquitous throughout nature and in many modern technologies. Because of their omnipresent nature, porous media are studied to one degree or another in almost all branches of science and engineering. This text is an outgrowth of a two-semester graduate course on multiscale porous media offered to students in applied math, physics, chemistry, engineering (civil, chemical, mechanical, agricultural), and environmental and soil science. The text is largely based on Dr Cushmans' groups efforts to build a rational approach to studying porous media over a hierarchy of spatial and temporal scales. No other text covers porous media on scales ranging from angstroms to miles. Nor does any other text develop and use such a diversity of tools for their study. The text is designed to be self-contained, as it presents all relevant mathematical and physical constructs.