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

APP file extension

Mac OS X Application

Executable Files

ASX file extension

Microsoft ASF Redirector File

Video Files

BMP file extension

Bitmap Image File

Raster Image Files

DEB file extension

Debian Software Package

Compressed Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

DXF file extension

Drawing Exchange Format File

CAD Files

H file extension

C/C++/Objective-C Header File

Developer Files

HTML file extension

Hypertext Markup Language File

Web Files

LUA file extension

Lua Source File

Developer Files

PAGES file extension

Pages Document

Text Files

PPS file extension

PowerPoint Slide Show

Data Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RM file extension

Real Media File

Video Files

TXT file extension

Plain Text File

Text Files

VB file extension

VBScript File

Executable Files