Dry aging is a meat-processing technique in which whole cuts, most often beef, are hung or stored uncovered in a temperature- and humidity-controlled environment for one to several months so that natural enzymes break down connective tissue and surface moisture evaporates. The resulting product is described as dry aged.
Aging chambers are held at 34-38°F (1-3°C) and 80-85% humidity to allow controlled moisture loss while inhibiting harmful bacteria; longer aging, commonly 4-6 weeks or more, produces more pronounced flavor and tenderness. As the surface dries, it forms a firm, leathery "pellicle" or crust that is trimmed away before the meat is cut and cooked.
Dry aging differs from wet aging, in which meat is vacuum-sealed and aged in its own juices - faster and less wasteful, since there is no crust to trim, but it does not concentrate flavor to the same degree. Because of the space, time, and trim loss involved, dry aging is mostly done by specialty butchers, high-end restaurants, and dedicated home setups rather than at ordinary retail scale.