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

OTF file extension

OpenType Font

Font Files

DAT file extension

Data File

Data Files

DLL file extension

Dynamic Link Library

System Files

WMA file extension

Windows Media Audio File

Audio Files

VB file extension

VBScript File

Executable Files

DNG file extension

Digital Negative Image File

Camera Raw Files

BIN file extension

Binary Disc Image

Disk Image Files

MPG file extension

MPEG Video File

Video Files

PPS file extension

PowerPoint Slide Show

Data Files

PCT file extension

Picture File

Layout Files

RPM file extension

Red Hat Package Manager File

Compressed Files

7Z file extension

7-Zip Compressed File

Compressed Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

LNK file extension

Windows File Shortcut

System Files

PSD file extension

Adobe Photoshop Document

Raster Image Files