JAX-WS is the Java API for building web services that comply with XML and SOAP standards. It allows creating web services from POJOs using annotations and handles XML serialization and networking. The reference implementation is provided by Glassfish and includes JAXB for XML binding, JAXR for service registries, and WSIT for interoperability features like security and transactions. Developers can use dispatch clients for low-level access or dynamic proxies for an RPC-style interface.