Wave–particle duality

Wave–particle duality means that things like light and particles can act like both waves and particles. We usually think of things like light as waves because we can see them as a bright beam, but we can also think of light as particles called "photons". Particles like electrons can also act like waves and they make up things like electricity. It's like a roller coaster - the cars are particles, but the track is like a wave, so the cars have to follow the wave track to move around.