Questions pertaining to the (hand) tool used to turn screws.
Screwdrivers are used to turn (or drive) screws, thus fastening or unfastening the pieces the screw is connecting. The term screwdriver can apply to both the powered and manual version of the tool, although it is more widely used to refer to the manual version.
Screwdrivers come in a variety of drive types (e.g., Philips, Torx, Robertson), to fit the various sizes and shapes of screw heads. Some screwdrivers come with interchangeable tip, allowing the same handle to be used to drive multiple types of screw, in the same vein as a powered drill. Others are designed to drive only a single type of screw.
Some screwdrivers have a clutch to allow for precise torquing of screws.