A screw is a type of fastener that is commonly used to hold two or more objects together. It is a cylindrical-shaped metal rod with a helical ridge, or thread, running around its length. The thread on a screw allows it to be easily inserted into a hole or tapped into a material, such as wood or metal, and then tightened to hold the objects in place. Screws come in a wide variety of sizes and types, such as flat head, pan head, and round head, each with their own unique applications. Screws are a simple yet essential tool that can be found in almost every industry and household.