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

APP file extension

Mac OS X Application

Executable Files

C file extension

C/C++ Source Code File

Developer Files

CLASS file extension

Java Class File

Developer Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

JAR file extension

Java Archive File

Executable Files

KMZ file extension

Google Earth Placemark File

GIS Files

LOG file extension

Log File

Text Files

MID file extension

MIDI File

Audio Files

OTF file extension

OpenType Font

Font Files

PART file extension

Partially Downloaded File

Misc Files

PY file extension

Python Script

Developer Files

RSS file extension

Rich Site Summary

Web Files

WMA file extension

Windows Media Audio File

Audio Files

XML file extension

XML File

Data Files