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

AVI file extension

Audio Video Interleave File

Video Files

CFM file extension

ColdFusion Markup File

Web Files

CRX file extension

Chrome Extension

Plugin Files

CS file extension

Visual C# Source Code File

Developer Files

DAT file extension

Data File

Data Files

FLA file extension

Adobe Flash Animation

Developer Files

FLV file extension

Flash Video File

Video Files

FON file extension

Generic Font File

Font Files

GADGET file extension

Windows Gadget

Executable Files

JAR file extension

Java Archive File

Executable Files

LOG file extension

Log File

Text Files

M file extension

Objective-C Implementation File

Developer Files

PY file extension

Python Script

Developer Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

3GP file extension

3GPP Multimedia File

Video Files