A+ Certification / Beginners

Compression utilities Extensions

Over the years, and across operating systems, file compression has always been an issue, leading to the creation of numerous different compression formats. Table below lists some of the common extensions for compressed files and where they are used. Although some utilities are based in one OS or another, today you can find compression and decompression tools for most formats in most operating systems.

Compression File Extensions
ExtensionTypeDescription
.aceAce or WinAceA new, high-compression format.
.arcArc or ArchiveTraditional Linux and Unix utility.
.arjArchiver Robert Jung - the creator of the formatTraditional archive utility for MS-DOS.
.bhx, .hqxBin-Hex filesBin-Hex is a Macintosh encoding format.
.cabCabinet fileA Microsoft format for distributing software.
.rarRoshal Archive - created by Eugene RoshalNew, high-compression format that is used on most operating systems.
.sitStuffITThe most popular Macintosh compression format.
.tarTape ARchive filesTraditional and highly used archive format for Linux and Unix. Short for "Tape Archive," it can back up directory structures into a single file, rather than compressing them. It is often used in conjunction with gzip.
.tgzTar-GZipTraditional and highly used compression format for Linux and Unix. This is actually a GZIPped TAR file.
.uu, .uueUUEncodeUUEncode is one of the most popular encoding algorithms for Linux and Unix.
.zipPK-ZIPThis is the grandfather of PC compression formats and is still the most used format for the MS-DOS and Windows worlds.

System files Extensions

Several types of files drive your computer's operating system. Some of the extensions you should expect to see on system files are listed in Table below.

System File Extensions
ExtensionTypeDescription
.386Windows-based driver filesHolds Windows formatted binary drivers.
.aniAnimated cursor filesContains animated mouse pointers.
.bakBackup filesUsed as a default extension by a number of applications.
.binBinary driversUsed for a few system drivers like drvspace.bin.
.cplControl Panel filesContains interface to adjust Windows settings
.curCursor filesHolds the graphical information to display your mouse cursor.
.da0Backed-up .dat filesUsed with the Registry files system.dat and user.dat.
.datData filesUsed with the Registry files system.dat and user.dat.
.dllDynamic Link LibraryContain common and reusable code that can be called by any application to reduce the amount of code that has to be placed within specific applications.
.drvMS-DOS or real-mode drive filesContains MS-DOS-formatted binary drivers
.iniInitialization filesText files that contain settings for applications; they are being phased out in favor of the Registry.
.mscMicrosoft Console settings filesYou will see this a lot with Windows 2000 or above and a bit with Windows NT 4.0.
.msgError message filesContain messages that are suppose to be displayed in the event of an error. These were used with the MSDOS network client, and were only required if you wanted to see a text description of error codes.
.msiMicrosoft Installer filesA new file format that is used to distribute software to computers that are running the Windows Installer service.
.scrWindows screen server filesHolds binary code to display Windows-based screen saver
.sysSystem driver filesUsed with MS-DOS and Windows for backward compatibility.
.ttfTrue Type Font definition filesContains formula description used to display scalable fonts
.vxdVirtual device driversHolds binary code for Windows-based device drivers
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