JAX-WS (Java API for XML Web Services) is a set of APIs provided by Java to develop and deploy web services. It enables developers to create SOAP-based web services, which can communicate with other platforms and languages. JAX-WS includes tools for generating WSDL (Web Services Description Language) files and client stubs, making it easier to develop and consume web services. It is an important skill for Java developers involved in web development and integration projects.