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

INDD file extension

Adobe InDesign Document

Layout Files

MSI file extension

Windows Installer Package

Misc Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

CUR file extension

Windows Cursor

System Files

MPA file extension

MPEG-2 Audio File

Audio Files

PL file extension

Perl Script

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

TIF file extension

Tagged Image File

Raster Image Files

ODT file extension

OpenDocument Text Document

Text Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

VOB file extension

DVD Video Object File

Video Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DOC file extension

Microsoft Word Document

Text Files