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

TIFF file extension

Tagged Image File Format

Raster Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

HTM file extension

Hypertext Markup Language File

Web Files

MP3 file extension

MP3 Audio File

Audio Files

IFF file extension

Interchange File Format

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files

ASF file extension

Advanced Systems Format File

Video Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

KMZ file extension

Google Earth Placemark File

GIS Files

CPL file extension

Windows Control Panel Item

System Files

CFM file extension

ColdFusion Markup File

Web Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

DNG file extension

Digital Negative Image File

Camera Raw Files

CSS file extension

Cascading Style Sheet

Web Files