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Liquid nitrogen is produced industrially in large quantities by fractional distillation of liquid air and is often referred to by the quasi-formula LN₂ (but is more accurately written N₂(l) ). It is a cryogenic fluid which can cause instant frostbite on direct contact with living tissue. When appropriately insulated from ambient heat it serves as a compact and readily transported source of nitrogen gas without pressurization. Further, its ability to maintain temperatures far below the freezing point of water as it boils at (77 K, -196 °C or -320 °F) makes it extremely useful in a wide range of applications as an open-cycle refrigerant, including;

• the immersion freezing and transportation of food products
• the cryopreservation of blood, reproductive cells (sperm and egg), and other biological samples and materials (see image at right)
• the cryonic preservation of humans and pets in the hope of future revival with molecular repair technology
• in the study of cryogenics
• for demonstrations in science education
• as a coolant for highly sensitive sensors and low-noise amplifiers
• in dermatology for removing unsightly or potentially malignant skin lesions such as warts and actinic keratosis
• as a cooling supplement for overclocking a central processing unit, a graphics processing unit, or another type of computer hardware
• as a cooling medium during machining of high strength materials.
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• A tank of liquid nitrogen, used to supply a cryogenic freezer (for storing laboratory samples at a temperature of about -150 Celsius).