A power screwdriver is a screwdriver that uses some form of power source to perform the work of driving screws, rather than relying on human muscle. Power screwdrivers generally operate under electric power, and while they may use standard wall outlet current, battery powered tools are by far more common. Battery powered screwdrivers can use standard batteries but are often equipped with a dedicated rechargeable battery. These tools have become very common and are a favorite of contractors, carpenters, and do-it-yourself enthusiasts all over the world.
A typical cordless screwdriver is the standard for all power screwdrivers. These tools often resemble a standard cordless drill, with a pistol grip configuration and a battery located at the bottom of the handle. Most tools of this type are equipped with a chuck system, like a standard drill, usually operable by hand, that allows the quick changing of bits. Bits for a power screwdriver are available in a huge array of sizes and shapes. Standard slotted and Phillips screwdrivers are in common use all over the world, but dozens of other shapes are possible, such as hex bits, star bits, square bits and even triangle bits.
Another type of power screwdriver is the inline cordless screwdriver. This type of cordless screwdriver is configured much like a standard screwdriver but with an enlarged handle that holds batteries, which can be standard disposable or rechargeable cells or a dedicated rechargeable battery pack. These types of power screwdriver generally do not have a chuck for holding bits, but still allow for changing bits by a simple snap-in function.
Many modern versions of these tools incorporate other functions as well. The most basic of these is the ability to reverse direction with a simple button or switch. Most inline cordless screwdrivers can be locked so as to function as a standard human powered tool if the batteries fail. Professional and other high end tools can have other features, like the ability to store bits on the tool, extra batteries, long battery life, adjustable speeds, and swiveling parts for hard to reach places and work lights.
Any standard power drill with an adjustable speed control can be used as a power screwdriver. By simply lowering the speed of the drill, which generally operates at much higher speeds than a typical power screwdriver, and using an interchangeable screwdriver bit, a power drill can quickly be converted for use in driving screws. These tools often require a chuck key to change bits and lose some of the quick change ability of dedicated cordless screwdrivers but still perform much better than old-fashioned human powered models.