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

AIF file extension

Audio Interchange File Format

Audio Files

ASPX file extension

Active Server Page Extended File

Web Files

CSR file extension

Certificate Signing Request File

Web Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

KMZ file extension

Google Earth Placemark File

GIS Files

MOBI file extension

Mobipocket eBook

eBook Files

MPA file extension

MPEG-2 Audio File

Audio Files

NES file extension

Nintendo (NES) ROM File

Game Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

ODT file extension

OpenDocument Text Document

Text Files

RA file extension

Real Audio File

Audio Files

ROM file extension

N64 Game ROM File

Game Files

SRT file extension

SubRip Subtitle File

Video Files

VCF file extension

vCard File

Data Files

VCXPROJ file extension

Visual C++ Project

Developer Files