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

MSG file extension

Outlook Mail Message

Text Files

WAV file extension

WAVE Audio File

Audio Files

KMZ file extension

Google Earth Placemark File

GIS Files

CS file extension

Visual C# Source Code File

Developer Files

TIFF file extension

Tagged Image File Format

Raster Image Files

MID file extension

MIDI File

Audio Files

TMP file extension

Temporary File

Backup Files

SYS file extension

Windows System File

System Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

PIF file extension

Program Information File

Executable Files

ZIP file extension

Zipped File

Compressed Files

HTM file extension

Hypertext Markup Language File

Web Files

JPG file extension

JPEG Image

Raster Image Files

CAB file extension

Windows Cabinet File

System Files

7Z file extension

7-Zip Compressed File

Compressed Files