Apache JAX-RS is a set of APIs to create RESTful web services in Java. It provides a standard way of developing services by using annotations and POJOs (Plain Old Java Objects) to handle HTTP requests and responses. JAX-RS supports different formats, including JSON and XML, and makes it easy to build scalable and efficient web services. It integrates well with other Java EE technologies like CDI (Contexts and Dependency Injection) and EJB (Enterprise JavaBeans). JAX-RS is ideal for building RESTful APIs in enterprise-grade applications due to its simplicity and extensibility.