A set screw, also known as a grub screw or adjustment screw, is a small fastener used to secure two parts together or to adjust the position of a part within a mechanism. Set screws come in various materials, including steel, stainless steel, brass, and plastic, depending on the application requirements. There are several types of set screws, including slotted set screws (with a single slot for a flat-head screwdriver), cross recessed set screws (with a cross-shaped recess for a Phillips screwdriver), and hex socket set screws (with an internal hexagonal socket for a hex key). Each type has its own advantages and is chosen based on the specific needs of the application.