1. Fuel: This is the substance that burns, providing the energy released in the reaction. Common fuels include:

* Hydrocarbons (like methane, propane, gasoline)

* Wood

* Ethanol

* Coal

* Natural gas

2. Oxidizer: This is a substance that provides the oxygen needed for the reaction to occur. The most common oxidizer is oxygen gas (O2).

Here's a basic chemical equation for combustion:

Fuel + O2 → Products (usually CO2 + H2O + energy)

Important Note: While oxygen is the most common oxidizer, other substances can act as oxidizers in certain situations, such as:

* Chlorine gas (Cl2): Can react with fuels like magnesium to produce heat and light.

* Fluorine gas (F2): Even more reactive than chlorine, it can support combustion with a wide variety of substances.

Let me know if you would like to explore specific examples of combustion reactions!