Sand is a fundamental substrate for modern life. It is a vital ingredient in the concrete that builds cities and infrastructures; suspended as a slow liquid with flux and stabilizer, it becomes the glass that composes everything from car windshields to smartphone screens; and often, as on Palm Beach, it is literally substrate, the ground beneath feet, homes, and cities. Beach sand is particularly valuable, increasingly scarce, and troublesomely wild. Florida is the peak expression of American beach culture. The state's 825 miles of beach reflect Florida's diversity. Florida's management plans establish "sand budgets" that attempt to describe, quantitatively and geographically, how each individual beach or inlet's sand-sharing system should function. Beaches are nourished with sand from a wide variety of sources, including inland mines, nearby ports with basins, slips, and channels, and offshore reservoirs. In even brief geologic time, all the assemblages of sand that appear in coastal environments are transient.