How and why things burn
...the kinetics and thermodynamics of combustion

Fire: the next three components form the fire triangle and are all necessary to sustain a fire

Heat: an energy source is necessary to ignite the sample (initiate burning) and sufficient energy must be produced by the flame to continue burning

Fuel: sample must produce fuel vapors (this may involve simple vaporization or thermal decomposition of the sample)

Oxygen: oxygen must mix with the fuel vapors and reaction will occur with sufficient energy (the chemical reaction is a complex mechanism that involves radicals)

Products: the combustion products are a mixture of hot gases and particulate matter that rise from the fire

Now let's go look at the stages of burning.