The simple motors you see explained in science books are based on a piece of wire bent into a rectangular loop, which is suspended between the poles of a magnet. (Physicists would call this a current-carrying conductor sitting in a magnetic field.) When you hook up a wire like this to a battery, a direct current (DC) flows through it, producing a temporary magnetic field all around it. This temporary field repels the original field from the permanent magnet, causing the wire to flip over. Normally the wire would stop at that point and then flip back again, but if we use an ingenious, rotating connection called a commutator, we can make the current reverse every time the wire flips over, and that means the wire will keep rotating in the same direction for as long as the current keeps flowing. That's the essence of the simple DC electric motor, which was conceived in the 1820s by Michael Faraday and turned into a practical invention about a decade later by William Sturgeon. (You'll find more detail in our introductory article on electric motors.)