Liquid nitrogen is a colorless, odorless liquid that is extremely cold, with a boiling point of -196 degrees Celsius (-321 degrees Fahrenheit). It is created by cooling and compressing nitrogen gas, which makes up about 78% of the Earth's atmosphere. Liquid nitrogen is commonly used in various applications, including cryogenics, food preservation, and medical procedures. When exposed to warmer temperatures, liquid nitrogen rapidly evaporates and turns back into nitrogen gas, creating a dramatic fog effect. This property makes it useful in scientific experiments and demonstrations. However, due to its extreme cold, it can cause severe frostbite if it comes into contact with skin, so safety precautions are essential when handling it.