Fire is the rapid oxidation of a fuel in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. Flames, Fire is the rapid oxidation of a fuel in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. Flames, the most visible portion of the fire, are produced in the combustion reaction when the fuel reaches its ignition point temperature. Flames from hydrocarbon fuels consist primarily of carbon dioxide, water vapor, oxygen, and nitrogen. If hot enough, t Fire is the rapid oxidation of a fuel in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. Flames, the most visible portion of the fire, are produced in the combustion reaction when the fuel reaches its ignition point temperature. Flames from hydrocarbon fuels consist primarily of carbon dioxide, water vapor, oxygen, and nitrogen. If hot enough, the gases may become ionized to produce plasma. The color and intensity of the flame depend on the type of fuel and composition of the surrounding gases. Fire, in its most common form, has the potential to result in conflagration, which can lead to permanent physical damage. Fire directly affects land-based ecological systems worldwide. The benefits of fire include stimulating plant growth and maintaining ecological balance. Its harms include hazards to life and property, atmospheric pollution, and water contamination. When fire removes protective vegetation, heavy rainfall can cause soil erosion. The burning of vegetation releases nitrogen into the atmosphere, unlike other plant nutrients such as potassium and phosphorus, which remain in the ash and are quickly recycled into the soil. This loss of nitrogen produces a long-term reduction in the fertility of the soil. However, it can be recovered by nitrogen-fixing plants—some of them of agricultural value, such as clover, peas, and beans, by decomposition of animal waste and corpses Fire is the rapid oxidation of a fuel in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. Flames, the most visible portion of the fire, are produced in the combustion reaction when the fuel reaches its ignition point temperature. Flames from hydrocarbon fuels consist primarily of carbon dioxide, water vapor, oxygen, and nitrogen. If hot enough, the gases may become ionized to produce plasma. The color and intensity of the flame depend on the type of fuel and composition of the surrounding gases. Fire, in its most common form, has the potential to result in conflagration, which can lead to permanent physical damage. Fire directly affects land-based ecological systems worldwide. The benefits of fire include stimulating plant growth and maintaining ecological balance. Its harms include hazards to life and property, atmospheric pollution, and water contamination. When fire removes protective vegetation, heavy rainfall can cause soil erosion. The burning of vegetation releases nitrogen into the atmosphere, unlike other plant nutrients such as potassium and phosphorus, which remain in the ash and are quickly recycled into the soil. This loss of nitrogen produces a long-term reduction in the fertility of the soil. However, it can be recovered by nitrogen-fixing plants—some of them of agricultural value, such as clover, peas, and beans, by decomposition of animal waste and corpses, and by natural phenomena such as lightning. Fire is one of the four classical elements and has been used throughout human history for purposes that now include cooking, generating heat and light, clearing land for agriculture, signaling, propulsion, smelting, forging, incineration of waste, cremation, rituals, weapons, and destruction, including in warfare. Various technologies and strategies have been devised to prevent, manage, mitigate, and extinguish fires, with professional firefighters playing a leading role. For example, most home fires start from unattended cooking, although cigarettes are another major cause. Smoke detectors and sprinkler systems greatly reduce harm from home fires. Fire is a chemical process in which a fuel and an oxidizing agent react, yielding carbon dioxide and water. This process, known as a combustion reaction, does not proceed directly and involves intermediates. Although the oxidizing agent is typically oxygen, other compounds can fulfill the role. For instance, chlorine trifluoride is able to ignite sand. Fires start when a flammable or a combustible material, in combination with a sufficient quantity of an oxidizer such as oxygen gas or another oxygen-rich compound (though non-oxygen oxidizers exist, such as chlorine), is exposed to a source of heat or ambient temperature above the flash point for the fuel/oxidizer mix, and can sustain a rate of rapid oxidation that produces a chain reaction. This is commonly called the fire tetrahedron. Fire cannot exist without all of these elements in place and in the right proportions. For example, a flammable liquid will start burning only if the fuel and oxygen are in the right proportions. Some fuel-oxygen mixes may require a catalyst, a substance that is not consumed, when added, in any chemical reaction during combustion, but which enables the reactants to combust more readily. Once ignited, a chain reaction occurs whereby fires can sustain their own heat through the continued release of heat energy during combustion and may propagate, provided there is a continuous supply of an oxidizer and fuel. If the oxidizer is oxygen from the surrounding air, the presence of a force of gravity, or of some similar force caused by acceleration, is necessary to produce convection, which removes combustion products and brings a supply of oxygen to the fire. Without gravity, a fire rapidly surrounds itself with its own combustion products and non-oxidizing gases from the air, which exclude oxygen and extinguish the fire. Because of this,