a good tool for applying torque to a screw
a superior tool for certain applications and the worst tool you could have for others
a tool that is used to put in and remove screws
An assortment of quality screwdrivers belongs in every toolbox. Slotted and Phillips blades are the most common -- buy several sizes of each. If you try to make do with a tip that's too small, you risk damaging the screw; if the tip is too wide, you'll damage the surrounding material as the screw is driven flush. Don't worry about the multitude of screwdrivers with specialty tips; buy them as the need arises. Home Improvement Encyclopedia
Tool with a shaped rod mounted in a handle. The end of the rod matches a slot or hole in a fastener. The most common and oldest is the slotted fastener where the rod is flattened and squared off at the end. Other shapes have been developed, most often to increase production or to reduce damage when the tool tears out of the slot or hole as force is applied. Phillips, Torx, square, Allen are other drives. The rod may be driven by a motor, in which case it is usually a tube with a 1/4" width hex interior to take driver bits.2003-12-07
Tool consisting of a handle on one end of the shank with a pointed blade on the other to install or remove screws. There are different blade ends for the different types of screws, such as Phillips Head, etc. Screwdrivers can be both manual and power driven (cord and cordless) and some have interchangeable bits to fit different head sizes.