A scroll wheel is a small, cylindrical device found on many computer mice. It allows users to easily navigate through long documents or web pages by rolling the wheel up or down. This simple action moves the content on the screen, making it quicker to find information without having to click and drag a scrollbar. In addition to scrolling, the scroll wheel often has additional functions. For example, pressing down on the wheel can act as a middle mouse button, which is useful for opening links in new tabs in web browsers like Google Chrome or Mozilla Firefox. This feature enhances productivity and user experience.