1. Conduction: Heat transfer through direct contact between substances. Think of a metal spoon heating up when you stir hot soup. The heat energy from the soup is transferred to the metal spoon molecules, causing them to vibrate faster and pass the heat along.

2. Convection: Heat transfer through the movement of fluids (liquids or gases). Imagine a pot of water boiling. The hot water at the bottom rises, while cooler water sinks to replace it, creating a continuous cycle of heat transfer.

3. Radiation: Heat transfer through electromagnetic waves. This is how the sun's energy reaches Earth. No physical contact is required, and heat can travel through a vacuum. A good example is how you feel the heat from a fireplace even though you're not directly touching it.