MIME是multipurpose Internet mail extensions 的缩写。它是一种协议，可使电子邮件除包含一般纯文本以外，还可加上彩色图片、视频、声音或二进位格式的文件。它要求邮件的发送端和接收端必须有解读 MIME 协议的电子邮件程序。
多媒体文件格式MIME
最早的HTTP协议中，并没有附加的数据类型信息，所有传送的数据都被客户程序解释为超文本标记语言HTML 文档，而为了支持多媒体数据类型，HTTP协议中就使用了附加在文档之前的MIME数据类型信息来标识数据类型。
MIME意为多目的Internet邮件扩展，它设计的最初目的是为了在发送电子邮件时附加多媒体数据，让邮件客户程序能根据其类型进行处理。然而当它被 HTTP协议支持之后，它的意义就更为显著了。它使得HTTP传输的不仅是普通的文本，而变得丰富多彩。
每个MIME类型由两部分组成，前面是数据的大类别，例如声音audio、图象image等，后面定义具体的种类。
常见的MIME类型
超文本标记语言文本.html text/html
普通文本 .txt text/plain
RTF文本 .rtf application/rtf
GIF图形 .gif image/gif
JPEG图形 .ipeg,.jpg image/jpeg
au声音文件 .au audio/basic
MIDI音乐文件 mid,.midi audio/midi,audio/x-midi
RealAudio音乐文件 .ra, .ram audio/x-pn-realaudio
MPEG文件 .mpg,.mpeg video/mpeg
AVI文件 .avi video/x-msvideo
GZIP文件 .gz application/x-gzip
TAR文件 .tar application/x-tar
Internet中有一个专门组织IANA来确认标准的MIME类型，但Internet发展的太快，很多应用程序等不及IANA来确认他们使用的 MIME类型为标准类型。因此他们使用在类别中以x-开头的方法标识这个类别还没有成为标准，例如：x-gzip，x-tar等。事实上这些类型运用的很 广泛，已经成为了事实标准。只要客户机和服务器共同承认这个MIME类型，即使它是不标准的类型也没有关系，客户程序就能根据MIME类型，采用具体的处 理手段来处理数据。而Web服务器和浏览器（包括操作系统）中，缺省都设置了标准的和常见的MIME类型，只有对于不常见的 MIME类型，才需要同时设置服务器和客户浏览器，以进行识别。
由于MIME类型与文档的后缀相关，因此服务器使用文档的后缀来区分不同文件的MIME类型，服务器中必须定义文档后缀和MIME类型之间的对应关系。而 客户程序从服务器上接收数据的时候，它只是从服务器接受数据流，并不了解文档的名字，因此服务器必须使用附加信息来告诉客户程序数据的MIME类型。服务 器在发送真正的数据之前，就要先发送标志数据的MIME类型的信息，这个信息使用Content-type关键字进行定义，例如对于HTML文档，服务器 将首先发送以下MIME标识信息,这个标识并不是真正的数据文件的一部分。
Content-type: text/html\r\n
MIME类型大全
MIME Type File Extension
application/SLA stl
application/STEP step
application/STEP stp
application/acad dwg
application/andrew-inset ez
application/clariscad ccad
application/drafting drw
application/dsptype tsp
application/dxf dxf
application/excel xls
application/i-deas unv
application/java-archive jar
application/mac-binhex40 hqx
application/mac-compactpro cpt
application/vnd.ms-powerpoint pot
application/vnd.ms-powerpoint pps
application/vnd.ms-powerpoint ppt
application/vnd.ms-powerpoint ppz
application/msword doc
application/octet-stream bin
application/octet-stream class
application/octet-stream dms
application/octet-stream exe
application/octet-stream lha
application/octet-stream lzh
application/oda oda
application/ogg ogg
application/ogg ogm
application/pdf pdf
application/pgp pgp
application/postscript ai
application/postscript eps
application/postscript ps
application/pro_eng prt
application/rtf rtf
application/set set
application/smil smi
application/smil smil
application/solids sol
application/vda vda
application/vnd.mif mif
application/vnd.ms-excel xlc
application/vnd.ms-excel xll
application/vnd.ms-excel xlm
application/vnd.ms-excel xls
application/vnd.ms-excel xlw
application/vnd.rim.cod cod
application/x-arj-compressed arj
application/x-bcpio bcpio
application/x-cdlink vcd
application/x-chess-pgn pgn
application/x-cpio cpio
application/x-csh csh
application/x-debian-package deb
application/x-director dcr
application/x-director dir
application/x-director dxr
application/x-dvi dvi
application/x-freelance pre
application/x-futuresplash spl
application/x-gtar gtar
application/x-gunzip gz
application/x-gzip gz
application/x-hdf hdf
application/x-ipix ipx
application/x-ipscript ips
application/x-javascript js
application/x-koan skd
application/x-koan skm
application/x-koan skp
application/x-koan skt
application/x-latex latex
application/x-lisp lsp
application/x-lotusscreencam scm
application/x-mif mif
application/x-msdos-program bat
application/x-msdos-program com
application/x-msdos-program exe
application/x-netcdf cdf
application/x-netcdf nc
application/x-perl pl
application/x-perl pm
application/x-rar-compressed rar
application/x-sh sh
application/x-shar shar
application/x-shockwave-flash swf
application/x-stuffit sit
application/x-sv4cpio sv4cpio
application/x-sv4crc sv4crc
application/x-tar-gz tar.gz
application/x-tar-gz tgz
application/x-tar tar
application/x-tcl tcl
application/x-tex tex
application/x-texinfo texi
application/x-texinfo texinfo
application/x-troff-man man
application/x-troff-me me
application/x-troff-ms ms
application/x-troff roff
application/x-troff t
application/x-troff tr
application/x-ustar ustar
application/x-wais-source src
application/x-zip-compressed zip
application/zip zip
audio/TSP-audio tsi
audio/basic au
audio/basic snd
audio/midi kar
audio/midi mid
audio/midi midi
audio/mpeg mp2
audio/mpeg mp3
audio/mpeg mpga
audio/ulaw au
audio/x-aiff aif
audio/x-aiff aifc
audio/x-aiff aiff
audio/x-mpegurl m3u
audio/x-ms-wax wax
audio/x-ms-wma wma
audio/x-pn-realaudio-plugin rpm
audio/x-pn-realaudio ram
audio/x-pn-realaudio rm
audio/x-realaudio ra
audio/x-wav wav
chemical/x-pdb pdb
chemical/x-pdb xyz
image/cmu-raster ras
image/gif gif
image/ief ief
image/jpeg jpe
image/jpeg jpeg
image/jpeg jpg
image/png png
image/tiff tif tiff
image/tiff tif
image/tiff tiff
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
model/iges iges
model/iges igs
model/mesh mesh
model/mesh msh
model/mesh silo
model/vrml vrml
model/vrml wrl
text/css css
text/html htm
text/html html htm
text/html html
text/plain asc txt
text/plain asc
text/plain c
text/plain cc
text/plain f90
text/plain f
text/plain h
text/plain hh
text/plain m
text/plain txt
text/richtext rtx
text/rtf rtf
text/sgml sgm
text/sgml sgml
text/tab-separated-values tsv
text/vnd.sun.j2me.app-descriptor jad
text/x-setext etx
text/xml xml
video/dl dl
video/fli fli
video/flv flv
video/gl gl
video/mpeg mp2
video/mp4 mp4
video/mpeg mpe
video/mpeg mpeg
video/mpeg mpg
video/quicktime mov
video/quicktime qt
video/vnd.vivo viv
video/vnd.vivo vivo
video/x-fli fli
video/x-ms-asf asf
video/x-ms-asx asx
video/x-ms-wmv wmv
video/x-ms-wmx wmx
video/x-ms-wvx wvx
video/x-msvideo avi
video/x-sgi-movie movie
www/mime mime
x-conference/x-cooltalk ice
x-world/x-vrml vrm
x-world/x-vrml vrml | 