I dropped the window key down a crack. I thought that a strong magnet would pull it out so I fetched one that I had salvaged from an old hard drive. It wouldn't fit into the crack because of the bits of hard drive arm still attached to it. So I found a screwdriver and attached the magnet to it. The screwdriver fitted into the crack and pulled up the key. The screwdriver is steel. It contains magnetic domains, areas of magnetism within the metal. The strong magnet was able to line these up temporarily so that they act together, turning the screwdriver into a temporary magnet. This is called induced magnetism.
