Science
What is Heat?
Heat is energy that flows from a hotter object to a cooler one because of their temperature difference. It's the transfer of thermal energy — the energy of moving particles — and it always moves from hot to cold until temperatures even out.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains heat.
Key things to understand
- 1Heat is energy in transit, flowing from higher to lower temperature.
- 2It's different from temperature: temperature measures how hot something is; heat is the energy that moves.
- 3Heat transfers three ways: conduction (contact), convection (moving fluids), and radiation (waves).
- 4Adding heat usually raises temperature or changes state (melting, boiling).
- 5Heat always flows hot → cold until both reach the same temperature (thermal equilibrium).
Frequently asked questions
- What's the difference between heat and temperature?
- Temperature measures how hot or cold something is (the average energy of its particles); heat is the total thermal energy that flows between objects of different temperatures. A spark is hot but carries little heat.
- How does heat move?
- Three ways: conduction (direct contact, like a pan handle warming), convection (warm fluids rising, like boiling water), and radiation (waves, like the Sun's warmth reaching us).
- Does cold flow, or just heat?
- Only heat flows — always from hot to cold. 'Cold' is just the absence of heat; something feels cold because heat leaves your hand and flows into it.