media-type

The MIME type of the resource or the data.

charset

The character encoding standard. Case insensitive, lowercase is preferred.

boundary

For multipart entities the boundary directive is required. The directive consists of 1 to 70 characters from a set of characters (and not ending with white space) known to be very robust through email gateways. It is used to encapsulate the boundaries of the multiple parts of the message. Often, the header boundary is prepended with two dashes and the final boundary has two dashes appended at the end.

In a POST request, resulting from an HTML form submission, the Content-Type of the request is specified by the enctype attribute on the <form> element.

<form action="/" method="post" enctype="multipart/form-data">
  <input type="text" name="description" value="some text" />
  <input type="file" name="myFile" />
  <button type="submit">Submit</button>
</form>

The request looks something like this (less interesting headers are omitted here):

POST /foo HTTP/1.1
Content-Length: 68137
Content-Type: multipart/form-data; boundary=---------------------------974767299852498929531610575

-----------------------------974767299852498929531610575
Content-Disposition: form-data; name="description"

some text
-----------------------------974767299852498929531610575
Content-Disposition: form-data; name="myFile"; filename="foo.txt"
Content-Type: text/plain

(content of the uploaded file foo.txt)
-----------------------------974767299852498929531610575--

• Accept
• Content-Disposition
• 206 Partial Content
• X-Content-Type-Options