A scroll bar 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 on the side or bottom of a window and consists of a sliding knob, or "thumb," that users can drag to move through the content. Scroll bars are commonly found in applications like web browsers, text editors, and image viewers. Scroll bars can be vertical or horizontal, depending on the direction of the content being scrolled. They provide visual feedback about the amount of content available and the user's current position within it. Users can also click on the arrows at either end of the scroll bar to move incrementally through the content.