The Content-Type Header Field
The Content-Type header field is used to specify the "type" and "subtype" of data in the body of a message and to fully specify the encoding of the data. There are seven main Content-Types, each with a growing number of subtypes. MIME has been carefully designed as an extensible mechanism, and it is expected that the set of content-type/subtype pairs and their associated parameters will grow significantly with time. Here are the seven main Content-Types along with currently defined subtypes.
Text A text Content-Type value can be used to represent textual information in a number of character sets and formatted text description languages in a standardized manner:
text/html html htm text/plain txt pl text/richtext rtx text/tab-separated-values tsv text/x-setext etx
Multipart A multipart Content-Type value can be used to combine several body parts, possibly of differing types of data, into a single message.
Multipart/Alternative This signifies multiple content-types with the same (or similar) information.
Multipart/Digest This signifies a series of included mail messages. Messages are of type message/RFC822 unless an explicit content-type is specified for each part.
Multipart/Mixed This signifies data with multiple content-types.
Multipart/Parallel This is similar to multipart/mixed data in parallel.
Application An application Content-Type value can be used to transmit application data or binary data, and hence, among other uses, to implement an electronic mail file transfer service:
application/octet-stream bin application/oda oda application/pdf pdf application/postscript ai eps ps application/rtf rtf application/x-mif mif application/x-maker fm application/x-csh csh application/x-dvi dvi application/x-hdf hdf application/x-latex latex application/x-netcdf nc cdf application/x-sh sh application/x-tcl tcl application/x-tex tex application/x-texinfo texinfo texi application/x-troff t tr roff application/x-troff-man man application/x-troff-me me application/x-troff-ms ms application/x-wais-source src application/zip zip application/x-bcpio bcpio application/x-cpio cpio application/x-gtar gtar application/x-shar shar application/x-sv4cpio sv4cpio application/x-sv4crc sv4crc application/x-tar tar application/x-ustar ustar
Message A message Content-Type value can be used for encapsulating another message in the document.
Message/RFC822 This signifies an included (MIME) mail message.
Message/News This signifies an included (MIME) USENET news message.
Message/Partial This signifies that the content is a single part of a message split into multiple mail messages.
Image This is an image Content-Type value for transmitting still image (picture) data:
image/gif gif image/ief ief image/jpeg jpeg jpg jpe image/tiff tiff tif image/x-cmu-raster ras image/x-portable-anymap pnm image/x-portable-bitmap pbm image/x-portable-graymap pgm image/x-portable-pixmap ppm image/x-rgb rgb image/x-xbitmap xbm image/x-xpixmap xpm image/x-xwindowdump xwd
Audio This is an audio Content-Type value for transmitting audio or voice data:
audio/bsic au snd audio/x-aiff aif aiff aifc audio/x-wav wav
Video This is a video Content-Type value for transmitting video or moving image data, possibly with audio as part of the composite video data format:
video/mpeg mpeg mpg mpe video/quicktime qt mov video/x-msvideo avi video/x-sgi-movie movie