Rare But Important File Extensions

What is PDF

The Portable Document Format (PDF) is the file format created by Adobe Systems in 1993 for document exchange. PDF is a fixed-layout format used for representing two-dimensional documents in a manner independent of the application software, hardware, and operating system. Each PDF file encapsulates a complete description of a 2-D document (and, with Acrobat 3-D, embedded 3-D documents) that includes the text, fonts, images, and 2-D vector graphics that compose the documents.

File Extension DAT

DAT file extension could represent following file types:

- Data file

- A data file extension used to designate an error message in a inbound internet email message (Microsoft Exchange Server v 5.0)

- WordPerfect Merge Data

- Extension used for some MPEG files

- Yahoo Messenger archive file

File Extension BIN

The .BIN/.CUE image file format was developed by Jeff Arnold for the CDRWIN program. An image consists of two files which contain binary data and metadata, respectively. The filenames typically match (e.g. image.bin and image.cue). The .BIN file contains an exact copy of all data stored on an optical disc in raw, unprocessed form but without any subchannel data. For this reason, some programs use the .RAW suffix for these files.

File Extension 3GP

3GP is a simplified version of the MPEG-4 Part 14 (MP4) container format, designed to decrease storage and bandwidth requirements in order to accommodate mobile phones. It stores video streams as MPEG-4 Part 2 or H.263 or MPEG-4 Part 10 (AVC/H.264), and audio streams as AMR-NB, AMR-WB, AMR-WB+ or AAC-LC.

File Extension XLS

XLS is a proprietary binary file format called Binary Interchange File Format (BIFF) as its primary format used by Excel to store spreadsheet information. Excel 2007 uses Office Open XML as its primary file format, an XML-based container similar in design to XML-based format called XML Spreadsheet (XMLSS), first introduced in Excel 2002.

TORRENT File Extension

BitTorrent (File Extension TORRENT) is a peer-to-peer file sharing (P2P) communications protocol. BitTorrent is a method of distributing large amounts of data widely without the original distributor incurring the entire costs of hardware, hosting, and bandwidth resources. Instead, when data is distributed using the BitTorrent protocol, each recipient supplies pieces of the data to newer recipients, reducing the cost and burden on any given individual source, providing redundancy against system problems, and reducing dependence on the original distributor.

File Extension TMP

Temporary files may be created by computer programs for a variety of purposes; principally when a program cannot allocate enough memory for its tasks, when the program is working on data bigger than architecture's address space, or as a primitive form of inter-process communication.

MP4 File Extension

MPEG-4 Part 14, formally ISO/IEC 14496-14:2003, is a multimedia container format standard specified as a part of MPEG-4. It is most commonly used to store digital audio and digital video streams, especially those defined by MPEG, but can also be used to store other data such as subtitles and still images. Like most modern container formats, MPEG-4 Part 14 allows streaming over the Internet. The official filename extension for MPEG-4 Part 14 files is .mp4, thus the container format is often referred to simply as MP4.

BUP File Extension

BUP (Back UP) is the filename extension of some files stored on video DVDs. The BUP file is a backup of the IFO file on a DVD, which contains the information about the organization of tracks, menus, chapters, subtitles on the disc. The BUP files are used in the event that the corresponding IFO file is unreadable, perhaps due to a scratch on the surface of the disc.

SYS File Extension

In MS-DOS and DOS-based operating systems, these files can be used as configuration files for the operating system. The MSDOS.SYS and CONFIG.SYS files contain various configuration options. SYS files are also could be used as device drivers

THM File Extension

Small, icon-sized image used to represent a larger image; commonly used on the Web or in clip art galleries; may be created by various photo or video editing programs; also produced by some digital cameras as small sample images of photos saved on the camera.

PPT File Extension

Microsoft PowerPoint (file extension PPT) is a presentation program developed by Microsoft. It is part of the Microsoft Office system. Microsoft PowerPoint runs on Microsoft Windows and the Mac OS computer operating systems. It is widely used by business people, educators, students, and trainers and is among the most prevalent forms of persuasion technology. Beginning with Microsoft Office 2003, Microsoft revised branding to emphasize PowerPoint's identity as a component within the office suite. Microsoft began calling it Microsoft Office PowerPoint instead of merely Microsoft PowerPoint. The current version is Microsoft Office PowerPoint 2007. As a part of the Microsoft Office suite, PowerPoint has become the world's most widely used presentation program.

M4A File Extension

The existence of two different file extensions for naming audio-only MP4 files has been a source of confusion among users and multimedia playback software. Since MPEG-4 Part 14 is a container format, MPEG-4 files may contain any number of audio, video, and even subtitle streams, making it impossible to determine the type of streams in an MPEG-4 file based on its filename extension alone. In response, Apple Inc. started using and popularizing the .m4a file extension. Software capable of audio/video playback should recognize files with either .m4a or .mp4 file extensions, as would be expected, as there are no file format differences between the two. Most software capable of creating MPEG-4 audio will allow the user to choose the filename extension of the created MPEG-4 files.

BAK File Extension

File extension BAK is given to files used for backup of another document, often created automatically by various programs or the operating system; for example, Windows may create BAK files for the System.ini and Win.ini files.

MOV File Extension

The QuickTime (.mov) file format functions as a multimedia container file that contains one or more tracks, each of which stores a particular type of data: audio, video, effects, or text (for subtitles, for example). Each track either contains a digitally-encoded media stream (using a specific codec) or a data reference to the media stream located in another file. Tracks are maintained in a hierarchal data structure consisting of objects called atoms. An atom can be a parent to other atoms or it can contain media or edit data, but it cannot do both.

DB File Extension

Generic database file extension; could be created by a number of different database programs; may also be imported into multiple database programs.


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