File Extensions and Rules

File Extensions

File extensions are an important part of the name of a file.   Most of the software open a file with a fixed name of file extensions.  In case file extension is changed arbitrarily, the file may not open in the desired software and / or may termed as corrupted and thus data may be lost forever, if the user does not know how to set the same right.  Let us first understand basic concepts about Folders, Files and their extensions :-

What are Files / Folders / Directories :

Let us now learn about certain basic operations we need to do whenever we work on a computer. Suppose, we have created some document i.e. we have typed some document, then at the end of it, we would like the same to be saved for future reference or take print out. In order to save a new document or file, you must first choose the Save command. Most modern software place this command in a menu which you can access with the mouse button or Alt key. When one such document is saved it is called a file. While saving the document, it will ask you about the name you wish to give to this new document. Alongwith giving a name to this file, the user has a choice to decide as to where such a file should be saved. Such files can be saved within a Folder or Directory. Thus while giving a new name to the file, users must also choose a directory and/or disk to store the file in. Some software programs will automatically save files in specific directory that is created when the program is installed (default settings).

Modern software place this command in a menu which you can access with the mouse button or Alt key. When one such document is saved it is called a file. While saving the document, it will ask you about the name you wish to give to this new document. Alongwith giving a name to this file, the user has a choice to decide as to where such a file should be saved. Such files can be saved within a Folder or Directory. Thus while giving a new name to the file, users must also choose a directory and/or disk to store the file in. Some software programs will automatically save files in specific directory that is created when the program is installed (default settings).

 Thus, a folder or directory can hold any number of files.

Sometimes, we install new software on our computer. In such cases also, the setup executable file automatically creates new directories / folders and stores all the software files in such newly created folders / directories.

Thus, we can say that user can create and delete directories or folders as the need arises. Older operating systems require that the directory be emptied of files before it can be deleted. When deleting / removing a directory, user must always check that no important files is left in such directory or sub-directory. You should delete the directory only after ensuring that it doesn’t contain files you still need.

You can easily move files from one folder or directory to another, through either the use menu commands or drag & drop using the mouse or a file utility

On the disk (it can be your hard disk, our floppy disc, CD or Pen Drive) you can create any number of directories / folders – each of such directories / folders can contain number of files. Moreover, These directories or folders could be compared to a filing cabinet. All files are stored in a directory / folder. Most hard disks have many directories or folders and files can be stored in any of them.

Directories can have sub-directories and sub-sub-directories many levels down. The directory immediately below the current directory is called the child directory. The directory immediately above the current one is called the parent directory. The top of the directory structure is called the root directory.

 Some common rules are:

• All files are saved on a disk or storage device.

• A disk is usually broken up into directories and sometimes into partitions.

• A directory or folder is a way of keeping like files in a common area.

Rules for File Names and Extension

Computers using DOS 6.X or older followed the 8.3 rule i.e. a filename can only be 1 to 8 characters long followed by a 1 to 3 character extension separated by a dot. Three character extensions are common because of this.

Modern operating systems allow computer users to use filenames up to 256 characters. Mac users, Windows 9X & NT/2000 and UNIX/LINUX (along with a few other) use long file names but names using over 32 characters get unwieldy. It is better to use a directory or folder to help describe them and keep common files together with shorter filenames.

Many modern software programs (applications) add their own extension to filenames. These extensions allow operating systems to recognize certain filenames and associate (match) them to the program that created it.

File Types, Appropriate Extensions  And Software Used to Open Such Files

Type of File	Extension	Used By Which Software
3D Image Files	.3dm	Rhino 3D Model
3D Image Files	.3dmf	QuickDraw 3D Metafile
Audio Files	.aac	Advanced Audio Coding File
Audio Files	.aif	Audio Interchange File Format
Audio Files	.iff	Interchange File Format
Audio Files	.m3u	Media Playlist File
Audio Files	.mid	MIDI File
Audio Files	.midi	MIDI File
Audio Files	.mp3	MP3 Audio File
Audio Files	.mpa	MPEG Audio File
Audio Files	.ra	Real Audio File
Audio Files	.ram	Real Audio Media
Audio Files	.wav	WAVE Audio File
Audio Files	.wma	Windows Media Audio File
Backup Files	.bak	Backup File
Backup Files	.gho	Norton Ghost Backup File
Backup Files	.old	Backup File
Backup Files	.ori	Original File
Backup Files	.tmp	Temporary File
Compressed Files	.deb	Debian Software Package
Compressed Files	.gz	Gnu Zipped File
Compressed Files	.pkg	Mac OS X Installer Package
Compressed Files	.rar	WinRAR Compressed Archive
Compressed Files	.sea	Self-Extracting Archive
Compressed Files	.sit	Stuffit Archive
Compressed Files	.sitx	Stuffit X Archive
Compressed Files	.zip	Zipped File
Data Files	.123	Lotus 1-2-3 Spreadsheet
Data Files	.csv	Comma Separated Values File
Data Files	.dat	Data File
Data Files	.db	Database File
Data Files	.dll	Dynamic Link Library
Data Files	.mdb	Microsoft Access Database
Data Files	.pps	PowerPoint Slide Show
Data Files	.ppt	PowerPoint Presentation
Data Files	.sql	Structured Query Language Data
Data Files	.wks	Microsoft Works Spreadsheet
Data Files	.xls	Microsoft Excel Spreadsheet
Data Files	.xml	XML File
Developer Files	.c	C/C++ Source Code File
Developer Files	.cpp	C++ Source Code File
Developer Files	.java	Java Source Code File
Developer Files	.pl	Perl Script
Disk Files	.dmg	Mac OS X Disk Image
Disk Files	.iso	Disc Image File
Disk Files	.toast	Toast Disc Image
Disk Files	.vcd	Virtual CD
Encoded Files	.bin	Macbinary II Encoded File
Encoded Files	.hqx	BinHex 4.0 Encoded File
Encoded Files	.mim	Multi-Purpose Internet Mail Message
Encoded Files	.uue	Uuencoded File
Executable Files	.app	Mac OS X Application
Executable Files	.bat	DOS Batch File
Executable Files	.cgi	Common Gateway Interface Script
Executable Files	.com	DOS Command File
Executable Files	.exe	Windows Executable File
Executable Files	.pif	Program Information File
Executable Files	.vb	VBScript File
Executable Files	.ws	Windows Script
Font Files	.fnt	Font File
Font Files	.fon	Generic Font File
Font Files	.otf	OpenType Font
Font Files	.ttf	TrueType Font
Game Files	.gam	Saved Game File
Game Files	.nes	Nintendo (NES) ROM File
Game Files	.rom	N64 Game ROM File
Game Files	.sav	Saved Game
Graphical Interchange Format File	.ai	Adobe Illustrator File
Graphical Interchange Format File	.drw	Drawing File
Graphical Interchange Format File	.dxf	Drawing Exchange Format File
Graphical Interchange Format File	.eps	Encapsulated PostScript File
Graphical Interchange Format File	.jpeg	JPEG Image File
Graphical Interchange Format File	.jpg	JPEG Image File
Graphical Interchange Format File	.png	Portable Network Graphic
Graphical Interchange Format File	.ps	PostScript File
Graphical Interchange Format File	.psd	Photoshop Document
Graphical Interchange Format File	.psp	Paint Shop Pro Image File
Graphical Interchange Format File	.svg	Scalable Vector Graphics File
Graphical Interchange Format File	.tif	Tagged Image File
Image Files	.mng	Multiple Network Graphic
Image Files	.pct	Picture File
Misc Files	.msi	Windows Installer Package
Misc Files	.torrent	BitTorrent File
Misc Files	.yps	Yahoo! Messenger Data File
Page Layout Files	.indd	Adobe InDesign File
Page Layout Files	.pdf	Portable Document Format File
Page Layout Files	.qxd	QuarkXpress Document
Page Layout Files	.qxp	QuarkXpress Project File
Plugin Files	.8bi	Photoshop Plug-in
Plugin Files	.plugin	Mac OS X Application Plug-in
Plugin Files	.xll	Excel Add-In File
Raster Image Files	.bmp	Bitmap Image File
Raster Image Files	.gif	Graphical Interchange Format File
Settings Files	.cfg	Configuration File
Settings Files	.ini	Windows Initialization File
Settings Files	.reg	Registration Information
System Files	.cab	Windows Cabinet File
System Files	.cpl	Windows Control Panel
System Files	.cur	Windows Cursor
System Files	.dmp	Windows Memory Dump
System Files	.drv	Device Driver
System Files	.key	Security Key
System Files	.lnk	File Shortcut
System Files	.sys	Windows System File
Text Files	.doc	Microsoft Word Document
Text Files	.log	Log File
Text Files	.msg	Mail Message
Text Files	.rtf	Rich Text Format File
Text Files	.txt	Plain Text File
Text Files	.wpd	WordPerfect Document
Text Files	.wps	Microsoft Works Word Processor Document
Video Files	.3gp	3GPP Multimedia File
Video Files	.asf	Advanced Systems Format File
Video Files	.asx	Microsoft ASF Redirector File
Video Files	.avi	Audio Video Interleave File
Video Files	.mov	Apple QuickTime Movie
Video Files	.mp4	MPEG-4 Video File
Video Files	.mpg	MPEG Video File
Video Files	.qt	Apple QuickTime Movie
Video Files	.rm	Real Media File
Video Files	.swf	Macromedia Flash Movie
Video Files	.wmv	Windows Media Video File
Web Files	.asp	Active Server Page
Web Files	.css	Cascading Style Sheet
Web Files	.htm	Hypertext Markup Language File
Web Files	.html	Hypertext Markup Language File
Web Files	.js	JavaScript File
Web Files	.jsp	Java Server Page
Web Files	.php	Hypertext Preprocessor File
Web Files	.xhtml	Extensible Hypertext Markup Language File