Deep frying is a cooking

Cooking

Cooking is the process of preparing food by use of heat. Cooking techniques and ingredients vary widely across the world, reflecting unique environmental, economic, and cultural traditions. Cooks themselves also vary widely in skill and training...

 method in which food is submerged in hot oil

Cooking oil

Cooking oil is purified fat of plant origin, which is usually liquid at room temperature ....

 or fat

Fat

Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...

. This is normally performed with a deep fryer or chip pan

Chip pan

A chip pan is a deep-sided cooking pan used for deep-frying. Chip pans are named for their traditional use in frying chips ....

; industrially, a pressure fryer or vacuum fryer

Vacuum fryer

A vacuum fryer is a deep-frying device housed inside a vacuum chamber. It was originally developed for potato chip production.Vacuum fryers are fit to process low-quality potatoes that contain higher sugar levels than normal, as they frequently have to be processed in spring and early summer before...

 may be used.

Deep frying is classified as a dry cooking method because no water is used. Due to the high temperature involved and the high heat conduction of oil, it cooks food extremely quickly.
If performed properly, deep-frying does not make food excessively greasy, because the moisture

Moisture

Humidity is the amount of moisture the air can hold before it rains. Moisture refers to the presence of a liquid, especially water, often in trace amounts...

 in the food repels the oil.