A fire starts with the ignition of a substance by a source that provides the necessary heat to the substance. This source can be a matchstick, an electrical spark, or the effect of a burning lens, such as a magnifying glass. The required temperature for ignition depends on the material. Paper burns at temperatures starting from 190°C, wood at 280°C, and cotton at 450°C. Therefore, a pair of jeans does not catch fire quickly, while a piece of paper catches fire very quickly. Once a substance starts burning, its intensity depends on the supply of oxygen. For this reason, windows and doors of a building should always be kept closed in case of a fire.
