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

ASP file extension

Active Server Page

Web Files

C file extension

C/C++ Source Code File

Developer Files

FLV file extension

Flash Video File

Video Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

ICS file extension

iCalendar File

Misc Files

INI file extension

Windows Initialization File

Settings Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MP4 file extension

MPEG-4 Video File

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PS file extension

PostScript File

Vector Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

VB file extension

VBScript File

Executable Files

WAV file extension

WAVE Audio File

Audio Files

WMA file extension

Windows Media Audio File

Audio Files