# Message Formats ## Response Message Format All **response** messages **MUST** support an [`application/hal+json`](http://stateless.co/hal_specification.html) (HAL) format. ### Error Response Format The [`application/problem+json`](https://tools.ietf.org/html/rfc7807) (Problem Detail) **MUST** be used to communicate details about an error. ## Request Message Format **Request** messages with body **SHOULD** support a [`application/json`](http://www.json.org) (JSON) format. Where applicable, request message **SHOULD** also support the [`application/hal+json`](http://stateless.co/hal_specification.html) format. **Request** messages **MAY** also support the [`application/x-www-form-urlencoded`](https://tools.ietf.org/html/rfc1866#section-8.2.1) (URL Encoded) format.