Fire is the visible result of the chemical reaction called combustion. Fire is a great example of a chemical reaction that involves the movement of electrons from one substance to another, a process called oxidation. In order to continue burning, fire needs both oxygen (O) and a fuel source (such as wood), and it results in the creation of many new products, including carbon dioxide (CO2) and water (H2O). Fire emits great amounts of heat and light, and while it has many uses, fire can easily spread, becoming extremely dangerous.
Candles work because heat from the flame evaporates the wax into a gas. This gas is then burned as fuel by the fire.
Fire extinguishers work by replacing the oxygen (O2) around a fire with carbon dioxide (CO2). Curious to see this in action? Check out the Pourable Fire Extinguisher science experiment.
The color of a fire changes based on how much oxygen (O) is available: blue for higher oxygen levels and yellow when there is less oxygen.