Internet Media Type, MIME-Type (Multipurpose Internet Mail Extensions) or Content-Type

RFC:2046

Internet media types should be registered as described in RFC 4288.
https://www.iana.org/assignmen[...]es/media-types.xhtml

Content-Type: text/plain	

Media types:

1. application
2. audio
3. example
4. image
5. message
6. model
7. multipart
8. text
9. video