JavaServer Faces (JSF) is a Java specification for building component-based user interfaces for web applications. It simplifies the development integration of web-based user interfaces by providing a set of reusable UI components, a standard way to manage the state of these components, and a framework for handling user input. JSF is part of the Java EE (Enterprise Edition) platform and is designed to work seamlessly with other Java technologies. It promotes a model-view-controller (MVC) architecture, allowing developers to separate the application logic from the user interface, which enhances maintainability and scalability of web applications.