Web Design in a Nutshell, 3rd Edition

File (MIME) Types

Servers add a header to each document, which tells the browser the type of file it is sending. The browser determines how to handle the file based on that information—for example, whether to display the contents in the window, or to launch the appropriate plug-in or helper application.

The system for communicating media types closely resembles MIME (Multipurpose Internet Mail Extension) , which was originally developed for sending attachments in email . The server needs to be configured to recognize each MIME type to successfully communicate the media type to the browser.

If you want to deliver media beyond the standard HTML files and graphics (such as a Shockwave Flash movie or an audio file), you should contact your server administrator to be sure the server is configured to support that MIME type. Most common formats are built into current versions of server software, but if the format isn’t there already, the administrator can easily set it up if you provide the necessary information.

The exact syntax for configuring MIME types varies among server software; however, they all require the same basic information: type, subtype, and extension. Types are the most broad categories for files. They include text, image, audio, video, application, and so on. Within each category are a number of subtypes. For instance, the file type image includes the subtypes gif, jpeg, and the like. The extension refers to the file’s suffix, which the server uses to determine the file type and subtype. Not all extensions are standardized.

Table 4-1 lists the MIME type and subtype for common media types. The ASCII/binary information is provided to aid in making upload decisions.

Of course, new technologies and file types are emerging every day, so keep in mind that it is the web designer’s responsibility to make sure that for any new media type, the appropriate information is communicated to the server administrator. For a complete listing of registered MIME types, see the IANA (Internet Assigned Numbers Authority) site at http://www.iana.org/assignments/media-types/.

Table 4-1. MIME types and subtypes

Type/subtype	Extension	Description	ASCII/binary
application/excel	.xl	Microsoft Excel	B
application/mac-binhex40	.hqx	Mac BinHex archive	B
application/msword	.doc, .dot, .word,.w6w	Microsoft Word document	B
application/pdf	.pdf	Portable Document Format (Adobe Acrobat file)	B
application/postscript	.ai	PostScript viewer	A
application/postscript	.eps	Encapsulated PostScript	A
application/postscript	.ps	PostScript file	A
application/powerpoint	.ppt, .pot	PowerPoint file	B
application/rtf	.rtf	Rich Text Format (Microsoft Word)	A
application/vnd.ms-excel	.xll, .xls	Microsoft Excel File	B
application/xml	.xml	Generic XML	A
application/xml+xhtml	.htm, .html	XHTML document	A
application/x-director	.dcr, .dir, .dxr	Shockwave files	B
application/x-gzip	.gz, .gzip	GNU zip (Unix decompressor)	B
application/x-msdownload	.exe	Self-extracting file or executable	B
application/x-perl	.pl	Perl source file	A
application/x-sea	.sea	Self-extracting archive (StuffIt file)	B
application/x-sit	.sit	StuffIt archive	B
application/x-shockwave-flash	.swf	Shockwave Flash file	B
application/x-stuffit	.sit	StuffIt Archive	B
application/x-tar	.tar	Compressed file	B
application/x-zip or application/x-zip-compressed	.zip	Compressed file (decompress using WinZip or StuffIt on Mac)	B
audio/aifc	.aifc	Compressed AIFF file	B
audio/basic	.au	μ-law sound file	B
audio/basic	.snd	Digitized sound file	B
audio/midi or audio/x-midi	.mid	MIDI audio file	B
audio/x-aiff	.aif, .aiff	AIFF file	B
audio/x-mpeg	.mp3	MP3 audio file	B
audio/x-ms-wma	.wma	Windows Media audio file	B
audio/x-ms-wax	.wax	Windows Media audio metafile	B
audio/x-pn-realaudio	.ra, .ram	RealAudio file (and metafile)	B
audio/x-pn-realaudio-plugin	.rpm	RealAudio (plug-in)	B
audio/x-wav	.wav, .aiff	Windows WAV audio file	B
image/gif	.gif	Graphic in GIF format	B
image/jpeg	.jpg, .jpeg, .jpe,.jfif, .pjpeg, .pjp	Graphic in JPEG format	B
image/tiff	.tif, .tiff	TIFF image (requires external viewer)	B
image/x-MS-bmp	.bmp	Microsoft BMP file	B
image/x-photo-cd	.pcd	Kodak Photo CD image	B
image/x-pict	.pic	PICT image file	B
image/x-png or image/png	.png	Graphic in PNG format	B
image/x-portable-bitmap	.pbm	Portable bitmap image	B
text/html	.htm	HTML document	A
text/plain	.txt	ASCII text file	A
text/richtext	.rtx	Rich Text Format (Microsoft Word)	A
text/xml	.xml	Generic XML document	A
video/avi or video/x-msvideo	.avi	AVI video file	B
video/mpeg	.mpg, .mpe, .mpeg,.m1v, .mp2, .mp3,.mpa	MPEG movie	B
video/quicktime	.mov	QuickTime movie	B
video/quicktime	.qt	QuickTime movie	B
video/x-ms-asf	.asf	Windows Media (legacy)	B
video/x-ms-asx	.asx	Windows Media metafile (legacy)	B
video/x-ms-wmv	.wmv	Windows Media video file	B
video/x-ms-wmx	.wmx	Windows Media video metafile	B
video/x-sgi-movie	.movie	Silicon Graphics movie	B
x-world/x-vrml	.wrl, .wrz	VRML 3D file (requires VRML viewer)	B