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

DNG file extension

Digital Negative Image File

Camera Raw Files

DTD file extension

Document Type Definition File

Developer Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

EPUB file extension

Open eBook File

eBook Files

FNT file extension

Windows Font File

Font Files

H file extension

C/C++/Objective-C Header File

Developer Files

JSP file extension

Java Server Page

Web Files

LNK file extension

Windows File Shortcut

System Files

MSI file extension

Windows Installer Package

Misc Files

PAGES file extension

Pages Document

Text Files

PNG file extension

Portable Network Graphic

Raster Image Files

TAR file extension

Consolidated Unix File Archive

Data Files

TOAST file extension

Toast Disc Image

Disk Image Files

TTF file extension

TrueType Font

Font Files

3DM file extension

Rhino 3D Model

3D Image Files