Dictionary:
File Extensions

.001-.999
Part of a RAR archive that has been split into several smaller files, named as .001 (where XXX can be any number between 000 and 999). In order to extract such archive correctly, all RAR files need to be found. This is a less popular, more older way to pack a release.

.AC3 (Audio Codec 3 aka Dolby Digital 3rd Generation)
AC3 is't Dolby Digital's audio codec. The common version contains 5.1 channels (five primary speakers and an LFE channel), but the format supports Mono and Stereo usages as well. AC3 audio is used on pretty much every single retail DVD you will buy. To play back AC3 audio on your computer, you should install the AC3Filters. This will also play back AC3 audio in DivX or XviD files.

.ACE
Another compression file like RAR (see below).

.AVI (Audio Video Interleave)
AVI is a video format from Microsoft. Currently it's the most common file format for storing audio/video data on the PC. Also it's a standard video format in the scene. AVI itself doesn't specify how it should be encoded, so the audio/video can be stored in very various ways. Most commonly used video codecs that use AVI structure are XViD and DiVX. AVI can be played by almost any video viewing program. When it's coded with XViD or DiVX you'll need to download the codec to view it.

.AVS (Application Visualization System)
Digital video format based on Digital Video Interactive (DVI) technology; often created by Intel video software.

.BIN (Binary)
A .bin file has many uses. It is used by many virus scanners and anti-spyware software as an update file for example. One of the main uses of .bin files right now is the creating and burning of cd/dvd images. These image files are a full copy of the cd. When the cd is completely ripped to a .bin file, a .cue file is also created .BIN files are the most used cd image files today.

.BUP (Back-UP)
A BUP file is a DVD file that is a backup of the IFO files. They are only needed if the original ifo on disc gets corrupted.

.CCD (CloneCD control file)
The CCD file is simply an ASCII text file that holds information on the CD that is needed for the burning process. A .ccd file on its own is useless, there also must be the .sub file and the .img file. With all these 3 files the cd image can be burned or mounted.

.CDA (CD Audio track)
CDA files are the standard format of audio on a CD. It can be converted to your hard drive by a ripper mp3 files. The converted mp3 files are much smaller than the original .cda files. .CDA files can be converted by a lot of cd rip tools.

.CDI (CD Image)
An .cdi file is a complete copy of a cd or dvd, stored into 1 file.

.CUE (Cue Sheet Track)
When a cd is completely ripped to a .bin image file, a .cue file is also created that contains information on the .bin file for burning or mounting software. A .cue file is also created when a .bin file is actually made from files on a harddrive. A .cue file can be opened directly by many cd burning software titles. It provides information on the cd image file or on the audio that is important to the burning software (such as locations of track breaks, the separation of songs on an audio cd is the result after burning). A .cue file is for cd's, what a .mds is for dvd's.

.DAT (Data)
A .dat file has many uses. One of the most important uses of .dat files are VideoCD and SuperVideoCD data files. Typically a .dat file is found on VCD or SVCD disc contains MPEG-1 (in case of VCD) or MPEG-2 (SVCD) -encoded video and audio encoded in MP2 format. VCD .dat files can be played with virtually all standard video software players, but in order to play SVCD .dat files, the system needs to have an MPEG-2 codec installed or the player has to have an integrated MPEG-2 decoding that supports SVCDs.
Windows Media Player Classic

.DIVX
Old file format of .avi files encoded with the divx codec. See .avi at the top of the page.

.DIZ (Description In Zip)
File_id.diz is a plain text file containing a brief content description of an archive in which it is included.

.ECL (Encoder Control List)
You will often encounter these files if you are saving a project with the Cinema Craft Encoder (CCE). When opened in the Cinema Craft Encoder it loads the saved settings for input and output files.

.EXE (EXEcutable)
An executable Windows application file. This can be all software, from games to burning tools, but also cracks, patches and so on..

.GZ (GZip)
An extension used by GNU's version of ZIP, called gzip. The gzip program has its origins on UNIX machines, but it has been ported to most other computer types as well and is typically available for free under the terms of the GNU public license. Unlike, for example, .zip, gzip compresses a single file. gzip is often used in conjunction with .tar to create a compressed collection of files (.tar.gz or .tgz).

.IFO (InFOrmation)
An IFO file is a DVD information file that store information about chapters, subtitles and audio tracks. The main content of DVD-Video disc are the VOB files which contain the actual MPEG-2 audio, video and subtitle streams. BUP files are a backup of the .IFO files.

.IMDB (International Movie DataBase)
An .imdb file is a textfile with movie info. When a movie/dvd is uploaded to a site, a script automatically generates a .imdb file. The script searches the movie title on imdb.com and copies the movie info to the file. The file contains info such as the director, the actors, the plot and more.

.IMG (Image)
An .img file is a complete copy of a cd or dvd, stored into 1 file. If it's ripped with CloneCD the .img file should also be accompanied by a .ccd and a .sub file. .IMG files are one of the two most standard file formats for image files in the scene. It can be burned to a cd/dvd or virtually mounted.

.ISO
An .iso file is a complete copy of a cd or dvd, stored into 1 file. The extension comes from the full name of the CD-ROM and DVD-ROM file system specification, ISO 9660. .ISO files are one of the two most standard file formats for image files in the scene. It can be burned to a cd/dvd or virtually mounted.

.JAcheck
JA Checker is a utility to check if the supported compresses files uploaded to a site are good. Sometimes there can be CRC errors in some compresses files and the sfv checker will detect and report these in the dir the compressed files are being uploaded to. The ja check will create a file like this: -[100%]--[All-files-CRC-OK]--[49-files]--[100%]-. The .jacheck saves the check process of JaCheck.

.JPG/.JPEG (Joint Photographic Experts Group)
A JPG file is a commonly used standard method of compression for photographic images and not for movie files for which MPEG compression is used. JPEG is used for lossy compression of images, although, variations on the standard baseline JPEG allow for lossless compression. The file format which employs this compression is commonly also called JPEG; the most common file extensions for this format are .jpeg, .jfif, .jpg, .JPG, or .JPE although .jpg is the most common on all platforms.

.M2V
.m2v is an MPEG-2 video file that contains only the video related data. M2V files are normally destined to be muxed.M2Vs are created by demultiplexing an existing MPEG-2, or by converting another video format to MPEG-2.

.M3U (Mpeg version 3 Url)
A .m3u file basically is just a textfile that lists all mp3 files. If the .m3u file is loaded to a media player, the player plays the list of media files in the order they are listed in the playlist. It was originally implemented in Winamp but because of it's popularity today it's supported by almost every audio player.

.MDF
If it is a rather large file, e.g. 650 MB, then it is most likely a CD image. If it is a file of smaller size, see at the end of this article. These MDF image files are created using a CD/DVD CD/DVD image file editor (and CD burner and CD/DVD backup tool) called MagicISO Maker.

.MDS
The MDF file is a CD/DVD image file, and MDS is the corresponding catalog file. Basically .mds contains information for DVD burning software and tells what .iso/.mdf files it should burn to the DVDR disc, in which way and in which order.

.MIDI (Musical Instrument Digital Interface)
An industry-standard electronic communications protocol that defines each musical note or event in an electronic musical instrument or show device such as a synthesizer, precisely and concisely, allowing electronic musical instruments, computers and other show equipment to exchange data in real time. It's a common standard for monofoon (& polyfoon) ringtones.

.MNU (MeNU)
A .mnu file is a Menu File. Several programs use this file extension. DVD-Lab & DVD-Lab Pro use this file to save and load user created menus.

.MOV (MOVie)
A .mov file is an Apple Quicktime movie file. A .mov file functions as a multimedia container file that contains one or more tracks, each of which store a particular type of data, such as audio, video, effects, or text (for subtitles, for example). Each track in turn contains track media, either the digitally-encoded media stream (using a specific codec such as mp3, jpeg, divx) or a data reference to the media stored in another file or elsewhere on a network.

.MP3 (MPEG Audio Layer-3)
MP3 is a widely used technology for the compression and decompression of music. It's the most common music file format in the scene, there almost are no others. MP3's can be played with almost any music player.

.MP4 (MPEG Audio Layer-4)
MPEG-4 -encoded audio or video file, using MPEG-4's container format. MP4 files can be played by alternative systems like Apple computers and iPod's.

.MPG / MPEG
MPEG-1 or MPEG-2 -encoded video file. A video standard developed by MPEG Group. MPEG-2 is not a successor for MPEG-1, but an addition instead -- both of these formats have their own purposes in life; MPEG-1 is meant for medium-bandwidth usage and MPEG-2 is meant for high-bandwidth/broadband usage. Most commonly MPEG-2 is used in digital TVs, DVD's and SVCD's.

.MRC (MiRC Script)
A script file for mIRC.

.NFO (iNFO textfile)
A .nfo file is a textfile with information about a release. The files are designed by ASCII artists and can be read with Damn NFO Viewer or simply with notepad. They contain release information like the runtime of a movie or an installation guide (if software).

.NRG (Nero CD-Image)
A .NRG file is a complete copy of a cd put into 1 file. Nero Burning Rom can create and burn CD-Images with the extension .NRG. They can also be used by Alcohol 120% or Daemon Tools.

.PAR .PAR2 / .P01 (Parity ARchive volume set)
These files are part of the Parity Archive Volume Set. You'll encounter them often at newsgroups. They come with the original files of course with an index file at the beginning of a post and different sizes of volumes at the end of a post. These files can fill in gaps from corrupted or missing parts when downloading from a newsgroup. You can use these files with QuickPar.

.PLS (PLayliSt)
A playlist file, used by variety of mpe software and hardware players. A .pls file is like a .m3u file, it's just a list filenames of (typically audio, but any format is fine as long as the player supports it) files that should be played.

.PPF (Playstation Patch File)
The full name of this filetype makes you think it's just for playstation files, but this is not true. Originally it was developed for playstation releases but nowadays it's also used for others like dvd's. Like the name says it's patch file, able to patch the release you downloaded. It's often used to fix a bug in the original release, or to apply a trainer, or sometimes even as a crack.

.RAR
A rar file is a data compression archive format. The actual content is packed into a rar-archive. Ussually they are split to multiple rar volumes with a certain size (15 or 50 is standard). Scene releases are packed into rar files, but they are not compressed. The rar files have typically a file extension of .rar, but in case of multi-part files, the extension can also be in form of .r00, .r01, .r02, etc. or .001, .002, .003, etc.

.r01-.r99
Part of a RAR archive that has been split into several smaller files, named as .rXX (where XX can be any number between 00 and 99) and one .rar file. In order to extract such archive correctly, all RAR files need to be found. In the scene this is a common way to pack a release.

.RACESTATS
A .racestats file is an automatically generated file by topsites. When a release just has been released and gets raced to a site, the site generates a textfile with info about who is racing it, the amount of files and the average speed.

.ratDVD
A .ratDVD file has been created with the software ratDVD. ratDVD can compress an entire DVD movie to one single file including menus with full functionality, all extras, all audio tracks, all angles and any other material on the disc. The result .ratDVD file is usually several gigabytes smaller, but the quality is not so good. Also, it's packed and compressed a lot.

.SFV (Simple File Validator)
SFV stands for Simple File Validator and is used to check files if they became corrupt after transfer. It does this by doing a CRC (cyclic redundancy check). After the check it displays which files contain CRC-errors and therefore are corrupt. It's also used on FTP servers / sites to check the progress of downloads or uploads. Click here to read more about sfv-files .

.SRT (SubRip subTitle)
A .srt file is the standard subtitle format produced by SubRip and is supported by virtually all subtitle manipulation and playback tools.

.SSA (Sub Station Alpha subtitle)
A .ssa file is the standard subtitle format produced by Sub Station Alpha and is supported by virtually all subtitle manipulation and playback tools. .SSA files are rather common still, even tho they aren't technically as advanced as several competing subtitle formats, but the fact that .ssa files are compatible with several popular video manipulation tools, makes it popular, at least as a temporary format.

.SUB (Subtitle)
A .sub file is one of three files that make up a CloneCD Image File. There should also be a .img file and a .ccd file. A .SUB file stores sub channel data on all tracks of the CD. It must be used with the .IMG file and the .CCD file to properly burn the contents to a CD.

.TAR (Tape ARchive)
An archive file format used mostly in the Unix world. TAR is capable of storing the file system structure including file permissions and dates. TAR does not do any compression by itself, so it's not a compression format like, for instance, zip. One can compress tar archives using either a separate tool or commandline switches -j (bzip2), -z (gzip) or -Z (compress). The commandline switches are available in the GNU version of tar.

.TME1 (Tsunami Mpeg media Editor project)
TSUNAMI MPEG Media Editor was created by TMPG Inc. and it allows you to easily edit MPEG files (supports HD content).

.TORRENT
.torrent files are basically BitTorrent's equivalent to ed2k links used in eDonkey network. In essence, .torrent files include instructions for BitTorrent -compatible P2P clients where to find the "tracker" for the downloaded file, hashed checksum that verifies for the client that it is actually downloading the correct file, the full size of the file and the filename of the file. So, essentially .torrent files are very, very small files that simply contain some textual data about the file itself. Thus, downloading the torrent file itself takes only matter of seconds, if not milliseconds, but it is not the file that is downloaded from the P2P network. Instead, .torrent files are typically hosted on just standard web servers and can be even passed via email. But in a computer with a BitTorrent -compatible client installed in it, launching a .torrent file typically starts a process where the BitTorrent -compatible client first contacts the tracker described in the .torrent file and if the tracker server is found and "seeds" (people sharing the file in question) are available, launches a download process of the file described in the .torrent file.

.TS
A .ts file is an MPEG-2 Transport Stream file.

.TXT
A plain text document without any formatting data, readable on virtually all computer platforms and with all text editors and viewers in the world. In the scene it can contain all sorts of stuff, like serials and other codes.

.VAF
A .vaf file is a Video Information File. You would find these files often in a DVD2SVCD output folder when using the Cinema Craft Encoder (CCE) to encode MPEG-2 video with a Variable Bitrate (VBR).

.VOB (Video Object File)
It is one of the core files found on DVD-Video discs and contains the actual movie data. Basically VOB file is just a basic MPEG-2 system stream, meaning that it is a file that contains multiplexed MPEG-2 video stream, audio streams (normally AC3 and DTS formats) and subtitle streams.

.VPD
A .vpd file is a PhotoDVD Project File. PhotoDVD is a software application developed by VSO Software. It allows you to create clever slideshows out of a variety of different image files.

.WMV (Windows Media Video)
WMV is a generic name of Microsoft's video encoding solutions and doesn't necessarily define the technology what it uses -- since version 7 (WMV7) Microsoft has used its own flavour of MPEG-4 video encoding technology (not very surprising, it's not compatible with other MPEG-4 technologies). DivX video format is originally based on hacked WMV codec. The latest versions of WMV don't have much in common with MPEG-4 anymore, but use Microsoft's own video encoding technologies instead. The only releases which are in .WMV format are porn clips, since you download them as .WMV from the web and don't require a re-encode.

.XTODVD
A .XtoDVD file is a ConvertXtoDVD Project File. ConvertXtoDVD is software from VSO Software that allows you to convert multiple video formats into DVD files (VOB, IFO, BUP).

.XVID
Old file format of .avi files encoded with the xvid codec. See .avi at the top of the page for more info.

.ZIP
The ZIP file format is a popular data compression and archival format. A ZIP file contains one or more files that have been compressed or stored. The format was originally developed by Phil Katz, the founder of PKWARE, back in 1989. The first tool ever to use the compression method was called PKZIP, developed by Katz's company. Nowadays, .zip is almost exclusively used as the file extension for ZIP-compressed files.