A screwdriver is a tool used to drive a screw into a surface. An electric screwdriver is one that is powered by electricity. It can be corded or cordless, and may be fixed or adjustable. The electricity that powers the tool turns the driver automatically, driving the screw more quickly into the surface and eliminating the need for manual torque.
There are many types of electric screwdrivers and they are sold by a number of power tool manufacturers. Sizes vary, as do power and pricing levels. Light-duty electric screwdrivers are made for individual or homeowner use, while mid- and heavy-duty drivers are made for contractors, woodworkers and other professionals.
Some such drivers are dedicated screwdrivers. Others are actually drills, which include not only bits for driving screws, but also bits for functions such as drilling holes. Regardless of the style, most such drivers come with at least two bits: one for turning standard or slotted screws and one for turning Phillips-head screws. Bit kits may come with various sizes of each style and also might include bits for custom screw head types, such as hex-head screws.
An electric screwdriver might be corded or cordless. A corded driver has an electrical cord wired into the tool. This cord plugs into a standard electrical outlet and pulls its power from a building's electricity. These tools can be used constantly for long periods of time because the power supply is constant. The cord, however, can get in the way and limit the range of the electric screwdriver.
A cordless electric screwdriver runs off of battery power. These batteries might be the same types of batteries sold in stores and used in a variety of handheld electronic devices and toys. Alternatively, they might be specialty batteries that are specific to the tool. Custom batteries usually come with their own chargers, which have a cradle to receive the battery and a plug that hooks into an electrical outlet. When plugged in, the charger passes electricity through to the battery, which stores it for a period of time.
Cordless screwdrivers are not connected to a cord, making them easier to move around. They can only be used, however, for as long as the battery holds its charge. As the charge begins to run out, less power is delivered to the driver and it becomes less effective. Some such cordless drivers have battery packs that are interchangeable with other power tools made by the same manufacturer.