Gas cylinders are used to store compressed gases or compressed air.
One familiar sort of gas cylinder is described in Diving cylinder.
They are also used on land to store gases for many purposes in industry and medicine.
Gas cylinders are commonly used to store LP gas (Liquefied Petroleum Gas). LP gas is useful for a wide range of applications, including cooking and heating. Installing gas cylinders requires trained personnel, as improper handling can be hazardous.
They are familiar in the oxyacetylene torch.
Industrial cylinders usually have different valves from diving cylinders.
Gas cylinders are often color coded. See Bottled gas.