A screw is a simple yet essential fastener used to hold objects together. It has a spiral thread that wraps around a cylindrical shaft, allowing it to grip materials tightly when turned. Screws come in various sizes and types, making them suitable for different tasks, from assembling furniture to securing parts in machines. When you use a screw, you typically need a tool called a screwdriver to turn it. There are many types of screws, such as wood screws for joining wood and machine screws for metal applications. Their versatility makes screws a fundamental part of construction and DIY projects.