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

CFG file extension

Configuration File

Settings Files

DDS file extension

DirectDraw Surface

Raster Image Files

FNT file extension

Windows Font File

Font Files

GADGET file extension

Windows Gadget

Executable Files

INI file extension

Windows Initialization File

Settings Files

MPG file extension

MPEG Video File

Video Files

NES file extension

Nintendo (NES) ROM File

Game Files

OTF file extension

OpenType Font

Font Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

SQL file extension

Structured Query Language Data File

Database Files

TORRENT file extension

BitTorrent File

Misc Files

VCD file extension

Virtual CD

Disk Image Files

ZIP file extension

Zipped File

Compressed Files