A dialog box is a small window that appears on a computer screen to prompt the user for input or to provide information. It typically contains a message, options for the user to choose from, and buttons like OK or Cancel to confirm or dismiss the action. Dialog boxes are commonly used in software applications to facilitate user interactions, such as saving files or adjusting settings. These boxes help streamline communication between the user and the software, ensuring that important information is conveyed clearly. They can also include text fields, checkboxes, or dropdown menus, allowing users to enter data or make selections easily. Overall, dialog boxes enhance user experience by guiding actions and decisions within a program.