The last two decades have seen rapid growth in the number of reported nanoporous materials with novel architectures, including many compounds with physical and chemical properties that go beyond what was previously considered the boundaries for materials performance. They open up new horizons in practically all branches of engineering, physics, chemistry, biology, and medicine. Among those materials, metal-organic frameworks (MOFs) have been well publicized and the focus of a large research effort, as have other classes such as covalent organic frameworks (COFs), porous molecular organic solids, and other molecular framework materials. While their chemical nature is varied (built from a combination of organic and/or inorganic buildings blocks) and the nature of the interactions involved is very diverse (including coordinate covalent bonds, π-π stacking, hydrogen bonds, mechanical bonds, dispersive interactions, . . . ), they typically share one common feature: they are framework materials, based on well-defined rigid building blocks (also called secondary building units, or SBUs) linked together by relatively weaker interactions.