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

ASX file extension

Microsoft ASF Redirector File

Video Files

BAK file extension

Backup File

Backup Files

DEB file extension

Debian Software Package

Compressed Files

DOC file extension

Microsoft Word Document

Text Files

DXF file extension

Drawing Exchange Format File

CAD Files

ICO file extension

Icon File

System Files

PART file extension

Partially Downloaded File

Misc Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PY file extension

Python Script

Developer Files

RM file extension

Real Media File

Video Files

TARGZ file extension

Compressed Tarball File

Compressed Files

WAV file extension

WAVE Audio File

Audio Files

WMV file extension

Windows Media Video File

Video Files

XCODEPROJ file extension

Xcode Project

Developer Files

3DM file extension

Rhino 3D Model

3D Image Files