The flash point of a volatile liquid is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a liquid's flash-point requires an ignition source. This is not to be confused with the autoignition temperature, which requires no ignition source. At the flash point, the vapor may cease to burn when the source of ignition is removed. A slightly higher temperature, the fire point, is defined as the temperature at which the vapor continues to burn after being ignited. Neither of these parameters is related to the temperatures of the ignition source or of the burning liquid, which are much higher. The flash point is often used as one descriptive characteristic of liquid fuel, but it is also used to describe liquids that are not used intentionally as fuels. Flash point refers to both flammable liquids as well as combustible liquids. There are various international standards for defining each, but most agree that liquids with a flash point less than 60°C are flammable, and those above this temperature are combustible.