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

ASF file extension

Advanced Systems Format File

Video Files

ASPX file extension

Active Server Page Extended File

Web Files

CAB file extension

Windows Cabinet File

System Files

CFG file extension

Configuration File

Settings Files

COM file extension

DOS Command File

Executable Files

DLL file extension

Dynamic Link Library

System Files

FLV file extension

Flash Video File

Video Files

JAVA file extension

Java Source Code File

Developer Files

JS file extension

JavaScript File

Web Files

KMZ file extension

Google Earth Placemark File

GIS Files

NES file extension

Nintendo (NES) ROM File

Game Files

PART file extension

Partially Downloaded File

Misc Files

PY file extension

Python Script

Developer Files

RM file extension

Real Media File

Video Files

WSF file extension

Windows Script File

Executable Files