A scrollbar is a graphical user interface element that allows users to navigate through content that is too large to fit within a visible area. It typically appears as a vertical or horizontal bar on the side or bottom of a window, enabling users to scroll up, down, left, or right to view additional information. Scrollbars are commonly found in applications like web browsers, word processors, and image viewers. Scrollbars consist of a track and a thumb, which represents the current position within the content. Users can click and drag the thumb to move through the content or click on the track to jump to a specific location. They enhance usability by providing a simple way to access hidden information without resizing the window or changing the layout.