Some HTTP requests may contain a message body. This is additional data that the server will use to process the request. Message bodies are most often used in POST or PATCH and PUT requests, to provide new data that the server should apply to a resource.
Requests that include a message body should always include its length in bytes with
A message body is included after all headers and a double CRLF. An example PUT request with a body might look like this:
PUT /files/129742 HTTP/1.1\r\n Host: example.com\r\n User-Agent: Chrome/54.0.2803.1\r\n Content-Length: 202\r\n \r\n This is a message body. All content in this message body should be stored under the /files/129742 path, as specified by the PUT specification. The message body does not have to be terminated with CRLF.
TRACE requests must not include a message body.