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

DWG file extension

AutoCAD Drawing Database File

CAD Files

DXF file extension

Drawing Exchange Format File

CAD Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

ICNS file extension

Mac OS X Icon Resource File

System Files

ISO file extension

Disc Image File

Disk Image Files

JAR file extension

Java Archive File

Executable Files

KEY file extension

Keynote Presentation

Data Files

LNK file extension

Windows File Shortcut

System Files

TIFF file extension

Tagged Image File Format

Raster Image Files

TOAST file extension

Toast Disc Image

Disk Image Files

TXT file extension

Plain Text File

Text Files

VCXPROJ file extension

Visual C++ Project

Developer Files

WPD file extension

WordPerfect Document

Text Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3GP file extension

3GPP Multimedia File

Video Files