An Alert Box is a simple dialog window used in computer programming to display important messages or notifications to users. It typically contains a short message and an "OK" button that users can click to acknowledge the information. Alert boxes are commonly used in web development, particularly with languages like JavaScript, to inform users about errors, warnings, or confirmations. When an alert box appears, it pauses the execution of the script until the user responds. This ensures that the user sees the message before continuing with their actions on the webpage. Alert boxes are a straightforward way to enhance user interaction and improve the overall experience on websites.