The screw is a simple machine that changed the world in remarkable ways. In the 1440s, the screw was central to the success of the printing press, which allowed scientists and great thinkers around the world to share ideas. Today, screws are necessary to hold a variety of objects together, from chairs to light bulbs. They also manifest in the forms of ceiling fans and airplane propellers. With approachable text and an image gallery of recognizable objects that use this simple machine, this book allows early readers to understand the forces and STEM concepts that make screws vital to the modern world.