File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

AVI file extension

Audio Video Interleave File

Video Files

BAT file extension

DOS Batch File

Executable Files

CBR file extension

Comic Book RAR Archive

Compressed Files

CGI file extension

Common Gateway Interface Script

Executable Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

IFF file extension

Interchange File Format

Audio Files

M file extension

Objective-C Implementation File

Developer Files

MSI file extension

Windows Installer Package

Misc Files

PHP file extension

PHP Source Code File

Web Files

RA file extension

Real Audio File

Audio Files

RM file extension

Real Media File

Video Files

RTF file extension

Rich Text Format File

Text Files

SH file extension

Bash Shell Script

Developer Files

SRT file extension

SubRip Subtitle File

Video Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files