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

C file extension

C/C++ Source Code File

Developer Files

CLASS file extension

Java Class File

Developer Files

CPP file extension

C++ Source Code File

Developer Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

H file extension

C/C++/Objective-C Header File

Developer Files

MAX file extension

3ds Max Scene File

3D Image Files

MOBI file extension

Mobipocket eBook

eBook Files

MP3 file extension

MP3 Audio File

Audio Files

MPG file extension

MPEG Video File

Video Files

PCT file extension

Picture File

Layout Files

PL file extension

Perl Script

Developer Files

RA file extension

Real Audio File

Audio Files

SQL file extension

Structured Query Language Data File

Database Files

TIF file extension

Tagged Image File

Raster Image Files

WPS file extension

Microsoft Works Word Processor Document

Text Files