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Nature

Fire

What is fire?

· James MacDonald

Key facts

Definition Rapid oxidation of a fuel in combustion[1]
Type Exothermic chemical reaction[1]
Outputs Heat, light, and reaction products[1]
Required components Fuel, oxygen, and heat[3]

Fire is a chemical reaction called combustion, where a fuel reacts rapidly with oxygen, releasing heat and light. It is not a substance but a visible process.

Context

Fire is a chemical reaction, specifically combustion, in which a fuel reacts rapidly with oxygen and releases heat and light [1]. It is not a substance itself but a visible manifestation of the process [3]. The fire triangle names three needed components: fuel, heat, and oxygen or air [3]. Fire is an exothermic reaction, meaning it releases energy in the form of heat and light [1].

Documented claims

  • Fire is the visible effect of combustion. [2]
  • Fire can burn until one or more of the needed components are removed. [3]

Questions and answers

Is fire a substance?

No, fire is not a substance; it is a chemical reaction called combustion [3].

What does fire need to burn?

Fire needs fuel, heat, and oxygen or air to burn [3].

Sources

  1. Wildland Fire: What Is Fire? (U.S. National Park Service) — nps.gov (retrieved August 3, 2026)
  2. The role of fire on Earth - PMC — pmc.ncbi.nlm.nih.gov (retrieved August 3, 2026)
  3. Fire Dynamics | NIST — nist.gov (retrieved August 3, 2026)

Sources last checked August 3, 2026. · More in Nature