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

APK file extension

Android Package File

Executable Files

APP file extension

Mac OS X Application

Executable Files

BAK file extension

Backup File

Backup Files

FLV file extension

Flash Video File

Video Files

GPX file extension

GPS Exchange File

GIS Files

IFF file extension

Interchange File Format

Audio Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

OTF file extension

OpenType Font

Font Files

PAGES file extension

Pages Document

Text Files

PNG file extension

Portable Network Graphic

Raster Image Files

RM file extension

Real Media File

Video Files

ROM file extension

N64 Game ROM File

Game Files

SRT file extension

SubRip Subtitle File

Video Files

TOAST file extension

Toast Disc Image

Disk Image Files

VB file extension

VBScript File

Executable Files