Everything that happens in the world, from a gust of wind to your own heartbeat, involves energy. But what is it, exactly? In simple terms, energy is the power to do work or cause change. It's what makes things move, grow, or heat up.

Scientists group energy into two main types. This helps us understand how energy behaves. The first is energy that is actively doing something, and the second is energy that is stored and waiting to be used.

Any object that is moving has kinetic energy. A bicycle rolling down the street has kinetic energy. A bird flying through the air has it, too. Even the tiny particles that make up the air you breathe are constantly moving, so they have kinetic energy.

The amount of kinetic energy an object has depends on two things: its mass and its speed. A heavy truck moving at 50 miles per hour has much more kinetic energy than a small car moving at the same speed. And that car has more kinetic energy at 50 miles per hour than it does at 20.

So, if it moves, it has kinetic energy. A falling raindrop, a spinning top, a planet orbiting the sun—they all possess this energy of motion.

The other main type of energy is potential energy. This is stored energy that has the potential to cause change or do work. It’s like energy waiting for its cue to get going.

Imagine stretching a rubber band. The stretched band isn't moving, but you can feel the tension in it. That tension is stored energy. If you let it go, that potential energy is released, and the rubber band snaps back into place. The potential to move was there all along.

Other examples are all around us. A book sitting on a high shelf has potential energy because of its position. If it falls, that energy will be released. A compressed spring and the water held back by a dam are also great examples of potential energy.

Every object has energy, either in motion or stored up. Understanding these two basic types is the first step to seeing how energy works everywhere.