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

ASF file extension

Advanced Systems Format File

Video Files

ASX file extension

Microsoft ASF Redirector File

Video Files

DAT file extension

Data File

Data Files

GADGET file extension

Windows Gadget

Executable Files

IFF file extension

Interchange File Format

Audio Files

PPT file extension

PowerPoint Presentation

Data Files

SH file extension

Bash Shell Script

Developer Files

SLN file extension

Visual Studio Solution File

Developer Files

SYS file extension

Windows System File

System Files

THM file extension

Thumbnail Image File

Raster Image Files

TORRENT file extension

BitTorrent File

Misc Files

TXT file extension

Plain Text File

Text Files

ZIPX file extension

Extended Zip File

Compressed Files

3DM file extension

Rhino 3D Model

3D Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files