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

AI file extension

Adobe Illustrator File

Vector Image Files

BAK file extension

Backup File

Backup Files

CPL file extension

Windows Control Panel Item

System Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

H file extension

C/C++/Objective-C Header File

Developer Files

MP4 file extension

MPEG-4 Video File

Video Files

OTF file extension

OpenType Font

Font Files

PDB file extension

Program Database

Database Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

VCF file extension

vCard File

Data Files

WSF file extension

Windows Script File

Executable Files

3GP file extension

3GPP Multimedia File

Video Files