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

ASPX file extension

Active Server Page Extended File

Web Files

CGI file extension

Common Gateway Interface Script

Executable Files

DAT file extension

Data File

Data Files

DOC# file extension

Microsoft Word Document

Text Files

GAM file extension

Saved Game File

Game Files

JPG file extension

JPEG Image

Raster Image Files

M4A file extension

MPEG-4 Audio File

Audio Files

MID file extension

MIDI File

Audio Files

PHP file extension

PHP Source Code File

Web Files

RA file extension

Real Audio File

Audio Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SWF file extension

Shockwave Flash Movie

Video Files

TTF file extension

TrueType Font

Font Files

XML file extension

XML File

Data Files

ZIPX file extension

Extended Zip File

Compressed Files