A nutdriver is like a socket on the end of a screwdriver. You use it to unscrew nuts or bolts by hand.

Sometimes you need to get into a tight spot, or you don't need all the power of a ratchet wrench. Enter the nutdriver, a screwdriver handle with either a fixed-size or interchangeable socket on the end. You can't get a lot of oomph behind it, but it's faster to remove or install a bolt with your hands than with a ratchet wrench. For instance, if you are removing an oil pan (which can have up to 30 individual bolts holding it on), you can use a larger wrench to break the bolts free, then switch to a nutdriver to get them out of there fast. A set of nutdrivers is not an absolute necessity, but they can come in really handy and make your job go a little faster.