A notification bar is a user interface element commonly found in software applications and websites. It typically appears at the top or bottom of the screen and displays important messages, alerts, or updates. Users can receive notifications about new messages, system updates, or reminders, helping them stay informed without interrupting their workflow. These bars can be interactive, allowing users to click on notifications for more details or to take action. They are often customizable, enabling users to choose which notifications they want to see. Popular platforms like Android and iOS utilize notification bars to enhance user experience and engagement.