The chemistry of the element phosphorus offers a window into the diverse field of inorganic chemistry. Fundamental investigations into some simple molecules containing phosphorus reveal much about the ramifications of this element's position in the periodic table and that of its neighbors. Additionally, there are many phosphorus compounds of commercial importance, and the industry surrounding this element resides at a crucial nexus of natural resource stewardship, technology, and modern agriculture. Questions about our sources of phosphorus and the applications for which we deploy it raise the provocative issue of the human role in the ongoing depletion of phosphorus deposits, as well as the transfer of phosphorus from the land into the seas.