Two-pronged devices are commonly used for smaller gadgets like phone chargers while larger appliances typically come with a three-pronged cable.

Smart plugs can help track energy use, but they also consume some power themselves. Knowing the standby draw helps you plan better.

You know the struggle: You go to plug something in, but the orientation's wrong. The prongs are different sizes, so you turn it the other way and try again. Still wrong. You finally get it, third time ...