HTTP: The Definitive Guide

Media Type and Charset

The Content-Type header field describes the MIME type of the entity body.^[7] The MIME type is a standardized name that describes the underlying type of media carried as cargo (HTML file, Microsoft Word document, MPEG video, etc.). Client applications use the MIME type to properly decipher and process the content.

The Content-Type values are standardized MIME types, registered with the Internet Assigned Numbers Authority (IANA). MIME types consist of a primary media type (e.g., text, image, audio), followed by a slash, followed by a subtype that further specifies the media type. Table 15-1 lists a few common MIME types for the Content-Type header. More MIME types are listed in Appendix D.

Table 15-1. Common media types

Media type	Description
text/html	Entity body is an HTML document
text/plain	Entity body is a document in plain text
image/gif	Entity body is an image of type GIF
image/jpeg	Entity body is an image of type JPEG
audio/x-wav	Entity body contains WAV sound data
model/vrml	Entity body is a three-dimensional VRML model
application/vnd.ms-powerpoint	Entity body is a Microsoft PowerPoint presentation
multipart/byteranges	Entity body has multiple parts, each containing a different range (in bytes) of the full document
message/http	Entity body contains a complete HTTP message (see TRACE)

It is important to note that the Content-Type header specifies the media type of the original entity body. If the entity has gone through content ...