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

DEB file extension

Debian Software Package

Compressed Files

JPG file extension

JPEG Image

Raster Image Files

MSG file extension

Outlook Mail Message

Text Files

ODT file extension

OpenDocument Text Document

Text Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PNG file extension

Portable Network Graphic

Raster Image Files

RM file extension

Real Media File

Video Files

SLN file extension

Visual Studio Solution File

Developer Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TORRENT file extension

BitTorrent File

Misc Files

VCXPROJ file extension

Visual C++ Project

Developer Files

VOB file extension

DVD Video Object File

Video Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3DM file extension

Rhino 3D Model

3D Image Files