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

LUA file extension

Lua Source File

Developer Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

M file extension

Objective-C Implementation File

Developer Files

DLL file extension

Dynamic Link Library

System Files

MP3 file extension

MP3 Audio File

Audio Files

FLA file extension

Adobe Flash Animation

Developer Files

TXT file extension

Plain Text File

Text Files

TMP file extension

Temporary File

Backup Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

WMV file extension

Windows Media Video File

Video Files

KEY file extension

Keynote Presentation

Data Files

SRT file extension

SubRip Subtitle File

Video Files

IFF file extension

Interchange File Format

Audio Files

DB file extension

Database File

Database Files