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

CGI file extension

Common Gateway Interface Script

Executable Files

DEB file extension

Debian Software Package

Compressed Files

M3U file extension

Media Playlist File

Audio Files

MOBI file extension

Mobipocket eBook

eBook Files

MOV file extension

Apple QuickTime Movie

Video Files

MSI file extension

Windows Installer Package

Misc Files

PIF file extension

Program Information File

Executable Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

ROM file extension

N64 Game ROM File

Game Files

RSS file extension

Rich Site Summary

Web Files

TAR file extension

Consolidated Unix File Archive

Data Files

TGA file extension

Targa Graphic

Raster Image Files

WSF file extension

Windows Script File

Executable Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files