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

BIN file extension

Binary Disc Image

Disk Image Files

CUE file extension

Cue Sheet File

Disk Image Files

DNG file extension

Digital Negative Image File

Camera Raw Files

KMZ file extension

Google Earth Placemark File

GIS Files

MPA file extension

MPEG-2 Audio File

Audio Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PY file extension

Python Script

Developer Files

RA file extension

Real Audio File

Audio Files

RTF file extension

Rich Text Format File

Text Files

SITX file extension

StuffIt X Archive

Compressed Files

SLN file extension

Visual Studio Solution File

Developer Files

TOAST file extension

Toast Disc Image

Disk Image Files

TTF file extension

TrueType Font

Font Files

VB file extension

VBScript File

Executable Files

3DS file extension

3D Studio Scene

3D Image Files