Video narration
How can a bicycle chain left alone turn orange? It looks like dirt stuck to the surface, or damage from ordinary wear. But rust is not something sitting on the metal. The metal itself is changing. Iron in steel reacts with substances around it. Water and oxygen commonly help drive that reaction, turning iron into rust. That is the key shift: rust is the metal being chemically changed by its surroundings. And rust is only one example of corrosion-the gradual damage that happens when a material reacts with its environment. Different materials can corrode in different ways, but exposure slowly changes what you started with. Drying metal, coating it, or blocking contact with water and air can slow the process. So how did that untouched chain become orange rust? Because water and oxygen reacted with its iron. That slow environmental attack is corrosion.