On this Wikipedia the language links are at the top of the page across from the article title. Not to be confused with Crackpot. Slow cookers achieved popularity in the US during the 1940s, when crockpot broccoli cheese soup women began to work outside the home. They could start dinner cooking in the morning before going to work and finish preparing the meal in the evening when they came home.

Naxon Beanery All-Purpose Cooker for the purposes of cooking a bean meal. The Rival Company from Sedalia, Missouri, bought Naxon in 1970, acquiring Naxon’s 1940 patent for the bean simmer cooker. Rival asked inventor Robert Glen Martin, from Boonville, Missouri, to develop Naxon’s bean cooker into a large scale production model which could cook an entire family meal, going further than just cooking a bean meal. A basic slow cooker consists of a lidded round or oval cooking pot made of glazed ceramic or porcelain, surrounded by a housing, usually metal, containing an electric heating element.

The “crock”, or ceramic pot, itself acts as both a cooking container and a heat reservoir. In the past, most slow cookers had no temperature control and deliver a constant heat to the contents. The temperature of the contents rises until it reaches boiling point, at which point the energy goes into gently boiling the liquid closest to the hot surface. At a lower setting, it may just simmer at a temperature below the boiling point. To use a slow cooker, the cook places raw food and a liquid, such as stock, water, or wine, in the slow cooker.

Some recipes call for pre-heated liquid. The cook puts the lid on the slow cooker and turns it on. The contents are enclosed by the crock and the lid, and attain an essentially constant temperature. The vapor that is produced at this temperature condenses on the bottom of the lid and returns as liquid, into which some water-soluble vitamins are leached. The liquid transfers heat from the pot walls to its contents, and also distributes flavors. The slow cooker’s lid is essential to prevent the warm vapor from escaping, taking heat with it and cooling the contents.

Basic cookers, which have only high, medium, low, or keep warm settings, must be turned on and off manually. Because food cooked in a slow cooker stays warm for a long time after it is switched off, people can use the slow cookers to take food elsewhere to eat without reheating. Some slow cookers have lids that seal to prevent their contents from spilling during transport. Recipes intended for other cooking methods must be modified for slow cookers. Quantities of liquids may need adjustment, as there is a little evaporation, but there should be enough liquid to cover the food. Cheaper cuts of meat with connective tissue and lean muscle fibers are suitable for stewing, and produce tastier stews than those using expensive cuts, as long slow cooking softens connective tissue without toughening the muscle.