Anyone who has ever connected a lamp to the mains knows the structure of a cable: inside the plastic sheath there are usually three wires: a green-yellow wire, the ground or protective conductor, a blue wire, the neutral conductor, and a current-carrying brown or black wire. A closer look reveals that each of these wires is made up of multiple twisted copper strands, fine, conductive strings of copper that can carry power and signals. This is the basic structure of every wire. But how do these components actually come together?