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

ACCDB file extension

Access 2007 Database File

Database Files

BIN file extension

Binary Disc Image

Disk Image Files

CSS file extension

Cascading Style Sheet

Web Files

DDS file extension

DirectDraw Surface

Raster Image Files

DMP file extension

Windows Memory Dump

System Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

IFF file extension

Interchange File Format

Audio Files

JAR file extension

Java Archive File

Executable Files

M3U file extension

Media Playlist File

Audio Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

SDF file extension

Standard Data File

Data Files

TAR file extension

Consolidated Unix File Archive

Data Files

VCF file extension

vCard File

Data Files

WMV file extension

Windows Media Video File

Video Files

3DM file extension

Rhino 3D Model

3D Image Files