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

ASPX file extension

Active Server Page Extended File

Web Files

BAT file extension

DOS Batch File

Executable Files

COM file extension

DOS Command File

Executable Files

CRX file extension

Chrome Extension

Plugin Files

ICNS file extension

Mac OS X Icon Resource File

System Files

LOG file extension

Log File

Text Files

M4V file extension

iTunes Video File

Video Files

PIF file extension

Program Information File

Executable Files

PY file extension

Python Script

Developer Files

RA file extension

Real Audio File

Audio Files

SAV file extension

Saved Game

Game Files

THM file extension

Thumbnail Image File

Raster Image Files

TTF file extension

TrueType Font

Font Files

VCF file extension

vCard File

Data Files

3GP file extension

3GPP Multimedia File

Video Files