A kitchen is a room or part of a room that is used for cooking and preparing food in a home or business. A modern middle-class residential kitchen is usually equipped with a stove, a sink with hot and cold running water, a refrigerator, and kitchen countertops and cabinets arranged in a modular design. Many homes have microwaves, dishwashers, and other electrical appliances. The main functions of a kitchen are to store, prepare, and cook food (and complete related tasks, such as washing dishes). The room or area can also be used for lunches (or small meals like breakfast), entertainment, and laundry. Kitchen design and construction is a huge market all over the world.
Commercial kitchens are found in restaurants, canteens, hotels, hospitals, educational and workplace facilities, army barracks, and similar facilities. These kitchens are generally larger and equipped with larger and heavier equipment than a residential kitchen. For example, a large restaurant might have a large refrigerator and large commercial dishwasher. In some cases, commercial kitchen equipment, such as commercial sinks, is used in domestic settings, offering ease of use for food preparation and long service life.  
In developed countries, commercial kitchens are generally subject to public health laws. They are periodically inspected by public health officials and forced to close if they do not meet the hygiene requirements imposed by law.
The evolution of the kitchen is linked to the invention of the hob or glass ceramic and the development of water infrastructures capable of supplying running water to private homes. Food was cooked over an open fire. Technical advances in food heating in the 18th and 19th centuries changed the architecture of the kitchen. Before the advent of modern plumbing, water came from an external source, such as wells, pumps, or springs.
Houses in ancient Greece were commonly of the atrium type: the rooms were arranged around a central courtyard for women. In many of these houses, a covered but open patio served as the kitchen. The houses of the wealthy had the kitchen as a separate room, usually next to the bathroom (so that both rooms could be heated by the kitchen fire), both rooms being accessible from the patio. In those homes, there was often a separate small laundry room at the back of the kitchen that was used to store food and kitchen utensils.
In the Roman Empire, common people in cities often did not have their own kitchen; they cooked in large public kitchens. Some had small portable bronze stoves, in which a fire could be lit for cooking. The wealthy Romans had relatively well-equipped kitchens. In a Roman villa, the kitchen was typically integrated into the main building as a separate room, separated for practical smoking and sociological reasons from the slave-run kitchen. Usually the fireplace was on the floor, set against a wall, sometimes a little raised, so you had to kneel to cook. There were no chimneys.