SAPUI5, or SAP User Interface 5, is a framework for building web applications with a rich user interface (UI) for SAP systems. It is based on HTML5, CSS, and JavaScript and offers a comprehensive set of UI controls, libraries, and development tools for creating responsive and modern web applications. SAPUI5 follows the Model-View-Controller (MVC) architecture, allowing for structured and modular development. It integrates seamlessly with SAP systems, enabling developers to access data and services from SAP back-end systems efficiently. SAPUI5 applications can run on various devices and platforms, providing a consistent user experience across different devices and screen sizes.