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

AIF file extension

Audio Interchange File Format

Audio Files

ASX file extension

Microsoft ASF Redirector File

Video Files

AZW file extension

Amazon Kindle eBook File

eBook Files

CBR file extension

Comic Book RAR Archive

Compressed Files

DAT file extension

Data File

Data Files

DNG file extension

Digital Negative Image File

Camera Raw Files

FLV file extension

Flash Video File

Video Files

ICNS file extension

Mac OS X Icon Resource File

System Files

INI file extension

Windows Initialization File

Settings Files

MDF file extension

Media Disc Image File

Disk Image Files

MOV file extension

Apple QuickTime Movie

Video Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

VCF file extension

vCard File

Data Files

YUV file extension

YUV Encoded Image File

Raster Image Files