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

APP file extension

Mac OS X Application

Executable Files

ASF file extension

Advanced Systems Format File

Video Files

C file extension

C/C++ Source Code File

Developer Files

CPL file extension

Windows Control Panel Item

System Files

CS file extension

Visual C# Source Code File

Developer Files

EPUB file extension

Open eBook File

eBook Files

FNT file extension

Windows Font File

Font Files

H file extension

C/C++/Objective-C Header File

Developer Files

M4A file extension

MPEG-4 Audio File

Audio Files

OTF file extension

OpenType Font

Font Files

PL file extension

Perl Script

Developer Files

PPS file extension

PowerPoint Slide Show

Data Files

ROM file extension

N64 Game ROM File

Game Files

SITX file extension

StuffIt X Archive

Compressed Files

TGA file extension

Targa Graphic

Raster Image Files