A screw has external threads just like a bolt. But a screw is inserted into a threaded or unthreaded hole, and is tightened or loosened by turning its head.

What objects have screws in them?

Some examples of the uses of a screw are in a jar lid, a drill, a bolt, a light bulb, faucets, bottle caps and ball point pens. Circular stairways are also a form of a screw. Another use of the screw is in a device known as a screw pump.

What screw are used for?

Screws are widely used in threaded fasteners to hold objects together, and in devices such as screw tops for containers, vises, screw jacks and screw presses. Other mechanisms that use the same principle, also called screws, don’t necessarily have a shaft or threads.