It's useful to have a few basic screwdrivers around the house. There are many simple household repairs that are much simpler to do with a screwdriver.
Generally a screwdriver has a handle and a blade -- the end that goes into the end of a screw to turn it. Screwdrivers come in different sizes from tiny ones for eyeglasses and jewelry to larger ones for regular construction screws.
Screwdrivers also have differently shaped ends or blades for different types of screws. A flat head screwdriver works with a screw that has a straight slot. A Phillips head screwdriver is more appropriate for a screw that has an x or 4 pointed star slot. Some screwdrivers have separate handles and "bits" or ends that can be interchanged and attached to the handle in order to fit different size and shape screws.
Some screwdrivers are powered. And some blades or bits are designed to be attached to a drill that will turn them. Other screwdrivers are ratcheted reducing the amount of work for the user. They only turn the screw in one direction and release when you turn your hand back for the next twist, so you don't need to keep taking the screwdriver out of the screw to adjust your hand and re-seat the screwdriver each time.
There's a cocktail named "screwdriver". The basic drink consists of vodka and orange juice -- usually twice as much orange juice as vodka. It's sometimes served over ice or another sweeter liquor is added as well.
- Wikipedia's article on screwdriver