special content filetypes require specialized software to use

File Types	Software Tool Suggestions
.ai	Adobe Illustrator must be used to edit these vector graphic files.
.aif, .aiff	Audio Interchange File Format (AIFF). Any media player or sound editor program can be used to view the .aif files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.asc	Any text editor can be used to view the .asc files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.avi	Media player software, such as QuickTime Player, RealOne Player, or Windows Media Player, is required to run the .avi files found on a course site.
.bat	Any text editor can be used to view the .bat files found on a course site. These files are also executable. Please refer to the course materials for any specific instructions or recommendations.
.bin	File decompression software, such as Winzip or StuffIt , is required to open the .bin files found on a course site.
.bmp	Any number of image viewers can be used to view the .bmp files found on a course site
.c	Any number of development tools can be used to compile and run the .c files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.cbp	Central Builder Project files are associated with C++ and can be opened with any text editor.
.cc	Any number of development tools can be used to compile and run the .cc files, C++ source code, found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.cif	A standard filetype sponsored by IUCr, used by various software and tools.
.cir	These files can be read using PSPICE Schematics, available from Cadence, Inc.
.class	Java Virtual Machine software (automatically installed in most major Web browsers) is required to run the .class files found on a course site.
.cnf	Any text editor can be used to view the .cnf files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.cpp	C++ source code can be opened with any text editor.
.coor	Any text editor can be used to view the .coor files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.csv	Any number of software tools can be used to import the .csv files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.ctd	MATLAB software is required to make use of the .ctd files found on a course site. NOTE: This is not a unique MATLAB extension. Please verify it is for use in MATLAB before using these statements.
.dat, .data	Any number of software tools can be used to import the .dat files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.db	.db files are generic database files that store data in a structured format. They can be read by any number of database programs.
.dbf	ArcView software is required to open and work with .dbf files, although they can also be opened with Microsoft Excel software.
.dcd	The DCD files are single precision binary FORTRAN files the format is supported by a wide range of analysis and display programs (such as VMD and NAMD).
.dcm	An image format created by the National Electrical Manufacturers Association (NEMA) as a standard for distributing and viewing medical images, such as MRIs, CT scans, and ultrasound images.
.dcr	Shockwave Player software is required to run the Shockwave media found on a course site.
.dll	Any number of programs can call the .dll files found on a course site. These files are also executable. Please refer to the course materials for any specific instructions or recommendations.
.dict	Any number of text editors can be used view the .dict files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.do	The STATA statistical package is required to view and run the .do files found on a course site.
.doc	Microsoft Word software is recommended for viewing the .doc files found on a course site. Free Microsoft Word Viewer software, OpenOffice Writer, and AbiWord can also be used to view the .doc files.
.ds	DataStudio Software is required to run the .ds files found on a course site.
.dta	The STATA statistical package is required to view and run the .dta files found on a course site.
.dvi	These are supporting files used in conjunction with TeX documents. No additional software is required if you can already open or edit the primary document file.
.dxf	These are supporting files that allow computer-aided design (CAD) projects to operate across many different software packages. No additional software is required if you can already open or edit the primary document file.
.el	Lisp source code is primarily associated with Emacs Lisp, a dialect of the Lisp programming language used by the GNU Emacs and XEmacs text editors. It can be opened with any text editor.
.eps	Ghostscript/Ghostview, Adobe Photoshop, and Adobe Illustrator are among the software tools that can be used to view the .eps files found on a course site.
.exe	The .exe files found on a course site are executable programs. Please refer to the course materials for any specific instructions or recommendations.
.fa, .fas, .fasta	Any number of biological sequence comparison software tools can be used to import the FASTA formatted sequence (.fa) files found on a course site.
FEFLOW	FEFLOW software is required to complete work on a course site.
.fig	MATLAB software is required to view and run the .fig files (MATLAB graphics files) found on a course site.
.fin	.fin fles are data offset tables and can be opened using any text edior.
.fits	Flexible Image Transport System (FITS) is a digital file format used to store, transmit, and manipulate scientific and other images. FITS is the most commonly used digital file format in astronomy. DS9 is an application that supports these files and is available for free download.
.f90	Any number of development tools can be used to compile and run the .f90 FORTRAN 90 files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.for	Any number of development tools can be used to compile and run the .for FORTRAN files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.fortran, .f	Any number of development tools can be used to compile and run the .fortran files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.fna	Any number of biological sequence comparison software tools can be used to import the FASTA formatted sequence (.fna) files found on a course site.
.gff	GFF is a format for describing genes and other features associated with DNA, RNA and protein sequences. The current specification and several software applications can be found here.
.gblorb	These compiled versions of .ni files can be run with an interpreter such as Frotz.
.gph	The STATA statistical package is required to view and run the .gph files found on a course site.
.gz	File decompression software, such as Winzip or StuffIt, is required to open the .gz files found on a course site.
.h	Header files for .c programs. Any number of development tools can be used to compile and run the .h files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.hs	Haskell compiler software is required to run the .hs files found on a course site.
.idb	This filetype is associated with ADINA, the FEA modeling software developed by Prof. Klaus-Jürgen Bathe.
.igs	.igs is a CAD translation standard ASCII text-based format for saving and exporting vector data.
.in	This filetype is associated with ADINA, the FEA modeling software developed by Prof. Klaus-Jürgen Bathe. Any text editor can be used to view the contents of the .in files found on a course site.
.iv	The ivview program from SGI Open Inventor toolkit is required to view the .iv files found on a course site.
.jar	Java plug-in software is required to run the Java files found on a course site.
.java	Any number of development tools can be used to compile and run the .java files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.jmp	JMP Statistical Discovery Software is required to run the JMP files found on a course site.
.jnlp	Java Web Start software is required to run the Java files found on a course site.
.jsim	JSim is a Java-based simulation system for building numeric models. Find instructions for using it here.
.key	Keynote, a component of iWork, is required for viewing .key files.
.kml	Keyhole Markup Language (KML) is an XML-based language schema for expressing geographic annotation and visualization on existing or future Web-based, two-dimensional maps and three-dimensional Earth browsers.
.lad	MATLAB software is required to make use of the .lad files found on a course site. NOTE: This is not a unique MATLAB extension. Please verify it is for use in MATLAB before using these statements.
.ldf	Microsoft SQL Server is required to make use of the .ldf files found on a course site. Free Microsoft SQL Server Express can also be used with the .ldf files.
.lib	These files can be read using PSPICE Schematics, available from Cadence, Inc.
.lisp	Allegro Common Lisp software is required to run the .lisp files found on a course site.
.loc	MATLAB software is required to make use of the .loc files found on a course site. NOTE: This is not a unique MATLAB extension. Please verify it is for use in MATLAB before using these statements.
.m	MATLAB software is required to run the .m files found on a course site. Additional toolbox plug-ins may also be required as noted on a course site. Any text editor can be used to view the contents of the .m files found on a course site.
.mat	MATLAB software is required to view and run the .mat files found on a course site.
.mcd	Mathcad software is required to view and run the .mcd files found on a course site.
.mdb	Microsoft Access software is recommended for viewing the .mdb files found on a course site. Free Microsoft Access viewer software can also be used to view the .mdb files.
.mdf	Microsoft SQL Server is required to make use of the .mdf files found on a course site. Free Microsoft SQL Server Express can also be used with the .mdf files.
.mdl	MATLAB software is required to run the .mdl files found on a course site.
.mf	These are metafont text or source files. To use these files, you need a typesetting program that can read the font such as TeX or Metafont. Please refer to the course materials for any specific instructions or recommendations.
.mid, .midi	TMedia player software, such as QuickTime Player, RealPlayer, or Windows Media Player is required to run the MIDI files found on a course site.
.mnc	MINC is a medical imaging oriented extension of the NetCDF file format. NetCDF stands for "Network Common Data Form" and it is widely used in many areas of scientific data storage.
.mod	Any number of programs can be used to run the .mod files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.mov	QuickTime Player software is required to view the .mov files found on a course site.
.movie	QuickTime Player software is required to view the .movie files found on a course site.
.mp	MetaPost is a picture-drawing language that outputs Encapsulated PostScript (.eps) files.
.mpp	Project management software, such as Microsoft Project is required to use these files.
.mp3	Media player software, such as QuickTime Player, RealOne Player, or Windows Media Player is required to run the .mp3 files found on a course site.
.mp4	The latest version of QuickTime Player can be used to run the .mp4 files found on a course site.
.mpeg, .mpg	Media player software, such as QuickTime Player, RealOne Player, or Windows Media Player is required to view these files.
.mph	COMSOL MULTIPHYSICS(formerly FEMLAB) is required to make use of the .mph files found on a course site.
.mpp	Project management software, such as Microsoft Project is required to use these files.
.mw	These files are Maple Worksheet files, for use with Maple software.
.nb	Mathematica software or the free MathReader software is required to run the .nb files found on a course site.
.net	.net files describe a network. Pajek is required to analyze and visualize .net files.
.ni	Structured text .ni can be read and edited with WordPad, Microsoft Word, or any other text editor. They are designed for use with Inform 7, a design system for interactive fiction.
OASES	OASES is a general purpose computer code for modeling seismo-acoustic propagation in horizontally stratified waveguides using wavenumber integration in combination with the Direct Global Matrix solution technique. It works with a variety of file types, including .par, .bdr, .cdr, .plp, .plt, .mtv, .trf and .rco.
.ord	OMAXÂ Software is required to run .ord files.
.oum	Any text editor can be used to view the contents of the .oum file on this course site. To use the .oum file as instructed on this page, MATLAB software is required.
.out	.out fles are data offset tables and can be opened using any text edior.
.p3	Primavera Project Planner software is required to run the .p3 files on a course site.
.pd	These are files for use in Pure Data, an open source real-time graphical programming environment for audio, video, and graphical processing.
.pdb	RasMol software is required to run the .pdb files found on a course site.
.pdb	Protein Data Bank viewer software can be used to view the .pdb protein data bank files found on a course site.
.pde	These files are associated with Processing, a programming language and environment for people who want to program images, animation and interactions.
.pddl	Any text editor can be used to view the .pddl files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.pl	A Perl interpreter is required to run the .pl files found on a course site.
.ppt	Microsoft PowerPoint software is recommended for viewing the .ppt files found on a course site. Free Microsoft PowerPoint viewer software can also be used to view the .ppt files.
.ps	Postscript viewer software, such as Ghostscript/Ghostview, can be used to view the .ps files found on a course site.
.psf	Any text editor can view these Protein Structure (.psf) files. They are generated by VMD Molecular Graphics Viewer and can be used with NAMD (Molecular Dynamics Simulator).
.py	Use the Python interpreter to run the .py files found on a course site.
.qif	MATLAB software is required to run the .qif files found on a course site. Any text editor can be used to view the contents of the .qif files found on a course site.
.r	Use R, an open source language and development environment for statistical computing, graphics, and exploratory data analysis, to run the .r files found on a course site.
.ram	RealOne Player software is required to run the .ram files found on a course site. There is a known issue with the Macintosh version of RealPlayer 11 that prevents the .ram files on the OCW/Highlights for High School sites from playing properly. Please download the RealPlayer 10 player here.
.rar	Files compressed using the .rar format can be extracted with the same software used to handle .zip (e.g., WinZip and StuffIt).
.rb	A Ruby interpreter is required to run the .rb files found on a course site.
.rm	RealOne Player software is required to run the .rm files found on a course site.
.rpt	.rpt is a report file. Generally, these are ASCII files and can be read using any text editor.
.rt	RealOne Player software is required to run the .rt files found on a course site.
.rtf	Rich Text Format files can be read with any of a number of common word processing programs such as Microsoft WordPad, Apple TextEdit, LibreOffice, OpenOffice.
.s	Assembly file. Any number of development tools can be used to compile and run the .s files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.sas7bdat	Base SAS software is required to open the .sas7bdat files found on a course site.
.scm	Scheme software is required to run the .scm files found on a course site.
.scs	Virtuoso Spectre software is required to run the .scs files found on a course site.
.sit	Stuffit is required to open the .sit files found on a course site.
.slb	These files can be read using PSPICE Schematics, available from Cadence, Inc.
.sldasm	SolidWorks software is required to run and view the .sldasm files found on a course site.
.sldprt	SolidWorks software is required to run and view the .sldprt files found on a course site.
.slddrw	SolidWorks software is required to run and view the .slddrw files found on a course site.
.slogo	StarLogo software is required to run the .slogo files found on a course site.
.smil	RealOne Player software is required to run the .smil files found on a course site.
.so	These are Unix shared library files. Any number of programs can call the .so files found on a course site. These files are also executable. Please refer to the course materials for any specific instructions or recommendations.
.spt	RasMol software is required to run the .spt files found on a course site.
.sql	These data files for SQL (Structured Query Language) can be edited using any text editor, and read by any SQL-compatible database program, including FileMaker, Microsoft Access and MySQL.
.stl	Computer-aided design (CAD) software is required to view the .stl files found on a course site.
.stp	Nanotec WSxM software is required to view the .stp file found on a course site.
.sty	These are supporting files used in conjunction with TeX documents. No additional software is required if you can already open or edit the primary document file.
.sub	Subcircuit files used in the LTSpice graphical SPICE simulator.
.swf	Flash Player software is required to run the Flash media found on a course site.
.swj	SolidWorks software is required to run and view the .swj files found on a course site.
.tar	File decompression software, such as Winzip or StuffIt, is required to open the .tar files found on a course site.
.tex	Software to view the .tex files on this course site can be accessed via the Comprehensive TeX Archive Network (CTAN) and the TeX Users Group Web site.
.textgrid	Pratt software is needed to make use of these plain text files that accompany corresponding sound files.
.tgz	File decompression software, such as Winzip or StuffIt , is required to open the .tgz files found on a course site.
.tif	Any number of image viewers can be used to view the .tif files found on a course site.
.uasm	A "micro" assembly language used in course 6.004. The files used in this course contain all information required to use them.
.ucf	Any number of text editors can be used to open and modify .ucf files. In many cases, they can also be used in an FPGA design and testing environment such as Xilinx ISE WebPACK.
.v	Any number of text editors can be used to open and modify .v files. In many cases, they can also be used in an FPGA design and testing environment such as Xilinx ISE WebPACK.
.vdf	These files are associated with Vensim Simulation Software, which is used for developing high-quality dynamic feedback models.
.vpp	These files are associated with Visual Paradigm, a series of software development applications. Product downloads are available from the Visual Paradigm website.
.vsd	Microsoft Visio software is recommended for viewing the .vsd files found on a course site. Free Microsoft Visio viewer software can also be used to view the .vsd files.
.vss	Microsoft Visio software is recommended for viewing the .vss stencil files found on a course site. Free Microsoft Visio viewer software can also be used to view the .vss files.
.vst	Microsoft Visio software is recommended for viewing the .vst template files found on a course site. Free Microsoft Visio viewer software can also be used to view the .vst files.
.wav	Media player software, such as QuickTime Player, RealOne Player, or Windows Media Player is required to run the .wav files found on a course site.
.wscp	Any text editor can be used to view the .wcsp files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.wk1	A Lotus123 worksheet that can be read directly into MATLAB. Lotus 123 or MATLAB software can be used to run the .wk1 files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.wm	Working Model 2D is required to view and run the .wm files found on a course site.
.wma	Media player software, such as RealOne Player, or Windows Media Player is required to run the .wma files found on a course site.
.wmv	Media player software, such as RealOne Player, or Windows Media Player is required to run the .wmv files found on a course site.
.x	Any number of development tools can be used to run the .x files found on a course site. Please refer to the course materials for any specific instructions or recommendations.
.xlo	.xlo is an AutoDesk Export Journal.
.xls, xlsx	Microsoft Excel software is recommended for viewing the .xls and .xlsx files found on a course site. Free Microsoft Excel viewer software can also be used to view the .xls and .xlsx files.
.xmcd	Mathcad software is required to view and run the .xmcd files found on a course site.
.xml	Any text editor can be used to view the .xml files found on a course site.
.xsl	Any text editor can be used to view the .xsl files found on a course site.
.xyz	VMD (Molecular Graphics Viewer) is used to to view and use .xyz files foudn on a course site.
.yaml	YAML files organize data in a human-readable text file, and may be viewed or edited using any text editor.
.zip	File decompression software, such as PKZIP , Winzip, or StuffIt, is required to open the .zip files found on a course site.

From: http://ocw.mit.edu/help/faq-technical-requirements/#cc