1. Fuel: This is the substance that burns, providing the energy source for the reaction. Common examples include wood, paper, gasoline, natural gas, and propane.

2. Oxidizer: This is the substance that reacts with the fuel, usually oxygen. Oxygen is the most common oxidizer, but others exist, such as chlorine and fluorine.

3. Heat (Ignition Source): This provides the initial energy needed to start the chemical reaction. The heat source can be a spark, flame, or even friction.

The Combustion Reaction:

The combustion reaction is a chemical process where the fuel reacts with the oxidizer, releasing heat and light. This reaction is typically exothermic, meaning it releases energy.

Here's a simple explanation:

Imagine a fire. The wood (fuel) reacts with oxygen in the air (oxidizer). A spark (heat) starts the reaction, and the fire burns, releasing heat and light.

Important Note: For combustion to occur, all three ingredients must be present in the correct proportions. For example, a fire will not start if there is no fuel or no oxygen.