That little “automatic” that adorns the fine-looking IWC dress watch at right? You can also find it on the faces and cases of iconic models from Rolex, Omega, Patek Philippe, and a host of others. And it means that, if you wear it regularly, you’ll never have to wind your timepiece by hand.
In any mechanical watch—one that isn’t powered by a battery—the power that keeps the second hand ticking (or sweeping) along comes from the mainspring, an internal spring which slowly releases tension to provide energy for the other components in the timepiece. When that mainspring goes slack, your chances of showing up late for that big dinner increase accordingly.
Back in the day, that meant your only option was to manually wind it back up as it unfurled. But with an automatic watch, you don’t have to bother. The watch does it for you, via a built-in semicircular weight that swings freely on a pivot and functions as a rotor. (It’s attached to a ratcheting mechanism so it only winds one way.) Every time you move your arm, you move the weight, and keep things running properly. If you plan on leaving your watch off for more than 36 hours or so, you’ll need to wind manually or invest in a specially designed case that’ll approximate the movement of your wrist, but if not, you’re in the clear. And those of you that talk with your hands needn’t worry about over-winding: An internal ”slipping clutch device” already does it for you. Convenient, no?