Dry aging beef is the proccess of storing certain beef cuts, fattier cuts (sirloin, ribeye etc) . you put the meats in racks in a temperature-humidity controlled environment. enzymes helps the fat break down in the meat which leaves a more tender cut of meat. moisture is also lost during this proccess so you lose, depending on the length of aging, some of the initial weight. the result is a more tender cut of meat with a unique "spunky" flavor. it is quite a bit more than a standard cut but well worth it! proccess is similiar to the making of Charcuterie meats(salami,pepperoni etc) although much different temp and humidity.