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

CFM file extension

ColdFusion Markup File

Web Files

CSS file extension

Cascading Style Sheet

Web Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

HTML file extension

Hypertext Markup Language File

Web Files

M4A file extension

MPEG-4 Audio File

Audio Files

MDF file extension

Media Disc Image File

Disk Image Files

PDB file extension

Program Database

Database Files

PL file extension

Perl Script

Developer Files

PPS file extension

PowerPoint Slide Show

Data Files

PPT file extension

PowerPoint Presentation

Data Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

SYS file extension

Windows System File

System Files

TAR file extension

Consolidated Unix File Archive

Data Files

VCF file extension

vCard File

Data Files

3DS file extension

3D Studio Scene

3D Image Files