The Content-Type header field in HTTP describes the body's content type present in the request and response messages. The content types are represented using standard internet media types. A RESTful web service makes use of this header field to indicate the type of content in the request or response message body. We discussed the Content-Type header fields in the Representing content types using HTTP header fields section in Chapter 1, Introducing the REST Architectural Style.

JAX-RS allows you to specify which internet media types of representation a resource can produce or consume by using the @javax.ws.rs.Produces and @javax.ws.rs.Consumes annotations, respectively. You will learn these two annotations with examples in this section.