Helper applications are separate programs that deal with files that your Web browser isn't equipped to handle. For example, there are helper applications that decode and decompress file archives, play special sound formats, and show animated movies. The "No Helper Application Defined" error message means you have run into a file that requires a helper application, and you either don't have the helper application or your Web browser doesn't know where to find it.

In most Web browsers, you can select helper applications in the "Preferences" or "Options" menu item, where you should see an option to choose "Programs," "Helpers," or "Viewers." Each file type will have a description which includes the file extension (like .txt for text or .wav for a WAV sound file), a content type (called the MIME type, which is server information that tells the browser what kind of information it is, like "text/plain" or "audio/x-wav"), and then the location and name of the helper application used to process that file. You will be able to modify existing helper applications, add new ones, and remove old ones.

Below is a partial list of file extensions and MIME-types that are supported by the imbris.net Web server. Again, the MIME-type tells the Web server how to send the file and tells the Web browser what kind of application to use to open the file. You can set up a helper application to view any of these files types with the Helper Application button. If a helper application has not been set up for one of these file types (or a file type not listed below), you will likely receive gibberish or an unreadable file that will be of no use to you.

.ai=application/postscript

.aif=audio/x-aiff

.aifc=audio/x-aiff

.aiff=audio/x-aiff

.art=image/x-art

.au=audio/basic

.avi=video/x-msvideo

.bin=application/octet-stream

.cdf=application/x-netcdf

.csh=application/x-csh

.dcr=application/x-director

.dir=application/x-director

.dvi=application/x-dvi

.dxr=application/x-director

.eps=application/postscript

.etx=text/x-setext

.exe=application/octet-stream

.fif=image/fif

.gif=image/gif

.gtar=application/x-gtar

.hdf=application/x-hdf

.hqx=application/mac-binhex40

.htm=text/html

.html=text/html

.ief=image/ief

.jpe=image/jpeg

.jpeg=image/jpeg

.jpg=image/jpeg

.js=application/x-javascript

.latex=application/x-latex

.ls=application/x-javascript

.man=application/x-troff-man

.me=application/x-troff-me

.mid=audio/x-midi

.mif=application/x-mif

.mocha=application/x-javascript

.mov=video/quicktime

.movie=video/x-sgi-movie

.mpe=video/mpeg

.mpeg=video/mpeg

.mpg=video/mpeg

.ms=application/x-troff-ms

.nc=application/x-netcdf

.oda=application/oda

.pbm=image/x-portable-bitmap

.pdf=application/pdf

.pgm=image/x-portable-graymap

.pnm=image/x-portable-anymap

.ppm=image/x-portable-pixmap

.ps=application/postscript

.qt=video/quicktime

.ra=audio/x-pn-realaudio

.ram=audio/x-pn-realaudio

.ras=image/x-cmu-raster

.rgb=image/x-rgb

.roff=application/x-troff

.rtf=application/rtf

.rtx=text/richtext

.sh=application/x-sh

.shar=application/x-shar

.snd=audio/basic

.spr=application/x-sprite

.sprite=application/x-sprite

.src=application/x-wais-source

.t=application/x-troff

.talk=text/x-speech

.tar=application/x-tar

.tcl=application/x-tcl

.tex=application/x-tex

.texi=application/x-texinfo

.texinfo=application/x-texinfo

.tif=image/tiff

.tiff=image/tiff

.tr=application/x-troff

.tsv=text/tab-separated-values

.txt=text/plain

.vmd=application/vocaltec-media-desc

.vmf=application/vocaltec-media-file

.vrml=x-world/x-vrml

.wav=audio/x-wav

.wrl=x-world/x-vrml

.xbm=image/x-xbitmap

.xpm=image/x-xpixmap

.xwd=image/x-xwindowdump