Some electrons only spin in circles around the molecule, but other electrons fly around freely. Like in the picture, water is made up of many loose molecules. These molecules do not join together as one object. This is why water changes its shape to match the shape of its container.

But in metals, all the molecules are strongly connected together. This is why metals are hard. It’s also why electrons can fly around freely inside the metal. These electrons are called free electrons. Free electrons normally move around in all different directions. But when they move and flow in a certain direction, that movement becomes electricity. So if someone asks you “What is electricity?”, you can answer: “Electricity is the flow of tiny particles called electrons that move around inside a metal wire”. Such flows of electrons can happen naturally. For example, have you ever been surprised by a sparking sound when you try to open a door? That is a kind of electricity called static electricity. But static electricity happens only with a small part of an object and only lasts a very short time. So static electricity can’t be used to light a light bulb, for example. The electricity we use every day is dynamic electricity, not static electricity. In other words, we can’t use electricity that doesn’t continually flow in a fixed direction with a nearly constant force. Generators are what produce the electricity we need.