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

BMP file extension

Bitmap Image File

Raster Image Files

CS file extension

Visual C# Source Code File

Developer Files

DEB file extension

Debian Software Package

Compressed Files

DLL file extension

Dynamic Link Library

System Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

EXE file extension

Windows Executable File

Executable Files

FON file extension

Generic Font File

Font Files

ICS file extension

iCalendar File

Misc Files

KEY file extension

Keynote Presentation

Data Files

MOBI file extension

Mobipocket eBook

eBook Files

MPA file extension

MPEG-2 Audio File

Audio Files

PDF file extension

Portable Document Format File

Layout Files

RSS file extension

Rich Site Summary

Web Files

VCXPROJ file extension

Visual C++ Project

Developer Files