Kosher salt, also sold as rock salt, is a type of coarse salt which is usually made without additives. The salt itself is not necessarily Kosher, but takes its name from the curing process used on Kosher meats. Kosher salt is ideal for certain cooking projects and is preferred to table salt by many professional chefs, because Kosher salt has a more mild flavor and the flaky crystalline structure of the salt helps it adhere to a variety of surfaces from fish to margarita glasses.

Like all salts, Kosher salt is a form of sodium chloride. Salt can be extracted from seawater by a direct evaporation process, or it can be mined from salt deposits under the Earth's crust. Table salt is heavily refined so that it has a precise square shape, and iodine is usually added during the refining process. Kosher salt is allowed to remain a more coarse-grained salt, meaning that the structure of Kosher salt under a microscope looks like a series of cubes stacked on top of each other, rather than a single grain.

Kosher salt is ideal for curing meats, because the many faces of the salt help to draw blood out of fresh meat. According to Jewish dietary laws, called Kashrut, blood cannot be consumed, even in small amounts. Meat with blood in it will not be approved for Jewish consumption by a rabbi and cannot carry a Kosher label. Kosher slaughterhouses use Kosher salt to extract all of the blood from their meat to ensure that the meat will comply with Kashrut. Many non-Kosher slaughterhouses use Kosher salt in their curing process as well, because the presence of blood can adversely affect the flavor of meat.

Because Kosher salt is not heavily refined or iodine treated, it has a flavor which many chefs consider to be more pure. For this reason, it is favored for seasoning in professional kitchens. The coarse grain of Kosher salt also allows chefs to measure out pinches of the salt with ease. Because of the large grain, kosher salt is not well suited to baking or table service, when fine grained salts are more appropriate.

In addition to being used for seasoning, Kosher salt is used to create salt crusts on baked fish, to create a salty rim on margarita glasses, and to rub meats along with other spices before cooking. Kosher salt is also used in pickling because the lack of iodine reduces the risk of discoloration and cloudiness. Most professional kitchens keep a stock of Kosher salt in small dishes around the kitchen so that it can be quickly and easily added to foods.

Kosher salt is readily available in most stores and restaurant supply houses. Generally the salt is comparable in cost to other salt varieties. A number of websites have information on how to use Kosher salt in cooking for curious cooks interested in experimenting with this seasoning option.