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

KMZ file extension

Google Earth Placemark File

GIS Files

MDB file extension

Microsoft Access Database

Database Files

TORRENT file extension

BitTorrent File

Misc Files

ASF file extension

Advanced Systems Format File

Video Files

MAX file extension

3ds Max Scene File

3D Image Files

CFM file extension

ColdFusion Markup File

Web Files

TIF file extension

Tagged Image File

Raster Image Files

APP file extension

Mac OS X Application

Executable Files

MSG file extension

Outlook Mail Message

Text Files

7Z file extension

7-Zip Compressed File

Compressed Files

CLASS file extension

Java Class File

Developer Files

SQL file extension

Structured Query Language Data File

Database Files

H file extension

C/C++/Objective-C Header File

Developer Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

TXT file extension

Plain Text File

Text Files