Fire is the visible effect of combustion, a chemical process where a material (called a fuel) reacts with oxygen in the air. This process needs three things to start and keep going — known as the fire triangle:

• Fuel – something that can burn, like wood, paper, gasoline, or gas.

  
  

• Oxygen – usually from the air.

  
  

• Heat – enough to start the reaction (called ignition temperature).

Once a fuel is heated to its ignition point, its molecules begin to break apart. These fragments combine with oxygen molecules in the air, and this triggers a chain reaction. Energy is released in the form of heat and light. That light is what we see as flames.

The heat keeps breaking apart more fuel molecules, which keeps the fire going.

The light and color of flames come from hot gases and small particles glowing as they react.

The main products of this reaction are usually carbon dioxide, water vapor, and other gases or tiny solid particles (like smoke or ash), depending on the fuel and how cleanly it burns.

If any part of the fire triangle is removed — fuel, oxygen, or heat — the fire will go out.