A classic brine is a mixture made of salt and water, and it can be used to preserve and/or flavor pretty much anything: vegetables, fruits, meats, fish. (You may also see foods “dry-brined,” which means they’re covered in salt, not immersed in salt water.) Brining meat for a few hours or days before cooking it makes for a juicier and more tender final product; the salt disrupts the structure of the muscle filaments, allowing the meat to absorb more liquid (and therefore lose less moisture while cooking) and keeping the proteins from coagulating as densely as they would naturally (and therefore preventing the meat from getting too tough). Brining fish for a short period of time has a similar effect, but you’ll also see fish brined for much longer; stuff like lox, anchovies, and salt cod are brined for weeks or months. In those cases, the salt transforms the fish into entirely new ingredients; the salt inhibits the bad bacteria from proliferating and aids in the proliferation of new savory compounds, creating more complex flavors and aromatics where there were none before.