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

CLASS file extension

Java Class File

Developer Files

CS file extension

Visual C# Source Code File

Developer Files

DMP file extension

Windows Memory Dump

System Files

DOC file extension

Microsoft Word Document

Text Files

DOC# file extension

Microsoft Word Document

Text Files

FNT file extension

Windows Font File

Font Files

GADGET file extension

Windows Gadget

Executable Files

MP4 file extension

MPEG-4 Video File

Video Files

PDB file extension

Program Database

Database Files

PL file extension

Perl Script

Developer Files

PNG file extension

Portable Network Graphic

Raster Image Files

SLN file extension

Visual Studio Solution File

Developer Files

WAV file extension

WAVE Audio File

Audio Files

ZIPX file extension

Extended Zip File

Compressed Files