There are several methods. Generally, industrial production of pure liquid nitrogen is achieved by distilling it from liquid air. Air is composed of oxygen (21%), nitrogen (78%), and a small percentage of other gases. To get the air to a liquid state, it undergoes a liquefaction process by means of strong compression by pistons that inject the air, and then it is cooled to very low temperatures. Some 700 liters of air in the gaseous state condense into just 1 liter of liquid air.
Nitrogen and other liquid gases are stored in Dewar containers, which are pressurized vessels that provide high thermal insulation.