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

SWF file extension

Shockwave Flash Movie

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

CSV file extension

Comma Separated Values File

Data Files

MPA file extension

MPEG-2 Audio File

Audio Files

MP4 file extension

MPEG-4 Video File

Video Files

MAX file extension

3ds Max Scene File

3D Image Files

SAV file extension

Saved Game

Game Files

ISO file extension

Disc Image File

Disk Image Files

TTF file extension

TrueType Font

Font Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

AZW file extension

Amazon Kindle eBook File

eBook Files

PL file extension

Perl Script

Developer Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

3G2 file extension

3GPP2 Multimedia File

Video Files