In a hot-electron device, the electrons that give the device its functionality have more energy than the rest of the electrons. It's as if those electrons were "hotter" than the rest (hence the name), although in our devices we give them their extra energy either by exciting them with photons or by quantum-mechanically shooting them through an insulating barrier. In our lab, we typically do one of three things with hot electrons: manipulate them with thin magnetic films, turn them into light (or both!), or use them to characterize the materials they pass through.