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

ACCDB file extension

Access 2007 Database File

Database Files

AIF file extension

Audio Interchange File Format

Audio Files

BAK file extension

Backup File

Backup Files

CAB file extension

Windows Cabinet File

System Files

CPP file extension

C++ Source Code File

Developer Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

MPA file extension

MPEG-2 Audio File

Audio Files

MPG file extension

MPEG Video File

Video Files

PL file extension

Perl Script

Developer Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

THM file extension

Thumbnail Image File

Raster Image Files

TMP file extension

Temporary File

Backup Files

WAV file extension

WAVE Audio File

Audio Files

3GP file extension

3GPP Multimedia File

Video Files