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

MSI file extension

Windows Installer Package

Misc Files

CAB file extension

Windows Cabinet File

System Files

SITX file extension

StuffIt X Archive

Compressed Files

VCXPROJ file extension

Visual C++ Project

Developer Files

MDB file extension

Microsoft Access Database

Database Files

MSG file extension

Outlook Mail Message

Text Files

7Z file extension

7-Zip Compressed File

Compressed Files

DEB file extension

Debian Software Package

Compressed Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

M file extension

Objective-C Implementation File

Developer Files

FLV file extension

Flash Video File

Video Files

EXE file extension

Windows Executable File

Executable Files

GPX file extension

GPS Exchange File

GIS Files

ZIPX file extension

Extended Zip File

Compressed Files

CLASS file extension

Java Class File

Developer Files