A deep fryer is a kitchen appliance used for frying. Deep frying is a cooking method that involves dipping food in oil over high heat, usually between 175 ° C and 190 ° C (350 ° F and 375 ° F).
Although commonly used in commercial kitchens, household models are available and have become more and more widespread.
Frying is well known in the United States, from frying sticks of butter to Twinkies, but the method can be traced back to Roman times.
Deep fryers usually have a basket to place the food in the oil tank and lift it when cooking is complete. Fryer baskets purchased separately are not standardized and, once selected, must be integrated into the fryer.  There are timers and alarms, automatic devices for raising and lowering the basket in the oil, ventilation systems to evacuate the frying odors from the kitchen, an oil filtration system or chemical treatment to improve reuse of the same amount of oil, and mechanical or electronic temperature controls that save energy and prevent fires by continuously detecting and adjusting oil temperature.