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

APP file extension

Mac OS X Application

Executable Files

BIN file extension

Binary Disc Image

Disk Image Files

CRX file extension

Chrome Extension

Plugin Files

CS file extension

Visual C# Source Code File

Developer Files

CUE file extension

Cue Sheet File

Disk Image Files

DDS file extension

DirectDraw Surface

Raster Image Files

DLL file extension

Dynamic Link Library

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

FLA file extension

Adobe Flash Animation

Developer Files

LNK file extension

Windows File Shortcut

System Files

MPA file extension

MPEG-2 Audio File

Audio Files

PL file extension

Perl Script

Developer Files

RM file extension

Real Media File

Video Files

SQL file extension

Structured Query Language Data File

Database Files

3DS file extension

3D Studio Scene

3D Image Files