If you've ever looked closely at an electrical plug, you've likely noticed that the ends of the prongs have little holes in them. While this is a leftover design element from early electrical systems, ...

There are 15 standardized types of domestic electrical outlet plugs in use worldwide. The standard North American outlet, for example, has two vertical slots and a round hole beneath them for ...

Hand holding a polarized power plug near a wall outlet with other devices already connected - Jannhuizenga/Getty Images If you've ever looked closely at an electrical plug, you've likely noticed that ...