A screwdriver is a hand tool used to turn screws, which are small metal fasteners that hold things together. The tool has a handle you grip and a narrow metal shaft that ends in a shaped tip. This tip fits into the groove or socket on top of a screw's head, letting you twist the screw clockwise to tighten it or counterclockwise to loosen it.

The two most common types are flathead screwdrivers, which have a single flat blade that fits into a straight slot, and Phillips screwdrivers, which have a cross-shaped tip that fits into an X-shaped socket. When you're assembling furniture, fixing a loose cabinet door, or taking apart a toy to see how it works, you'll likely reach for a screwdriver.

Using the right screwdriver matters. If you try forcing a flathead into a Phillips screw, you might strip the screw head, damaging the grooves so badly that no screwdriver can grip it anymore. A good screwdriver gives you control and leverage, turning a task that would be difficult with just your fingers into something manageable.