A screwdriver is a manual, handheld mechanical tool engineered to install or remove fasteners by transferring manual rotational force into torsional stress. Its structural architecture consists of three core components: an ergonomic handle made of high-impact plastic or rubberized composite to maximize grip friction, a rigid chrome-vanadium or carbon steel shank designed to withstand high twisting forces, and a precision-machined driving tip. This tip is specifically geometric—such as slotted, Phillips, or Torx—to match the exact profile of a corresponding screw head recess, and it is often hardened or magnetized to keep the fastener securely engaged.

Operation relies on axial alignment and precise torque application to drive or extract the fastener. To begin, the operator aligns the shank along the central axis of the screw and applies steady downward linear pressure to prevent the tip from slipping out and stripping the head recess. Rotating the handle clockwise turns the screw into a substrate until it sits completely flush, while rotating counter-clockwise backs the fastener out to loosen it.