JSF 2.3, or JavaServer Faces 2.3, is a framework used for building user interfaces in Java web applications. It simplifies the development process by providing reusable UI components and a clear separation between the presentation layer and business logic. This version enhances support for modern web standards and improves integration with other technologies. One of the key features of JSF 2.3 is its support for HTML5 and JSON, allowing developers to create more dynamic and responsive applications. Additionally, it introduces new annotations and improvements in the Facelets templating system, making it easier to manage complex user interfaces and improve overall performance.