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

PKG file extension

Mac OS X Installer Package

Compressed Files

PART file extension

Partially Downloaded File

Misc Files

KEY file extension

Keynote Presentation

Data Files

BIN file extension

Binary Disc Image

Disk Image Files

RM file extension

Real Media File

Video Files

DXF file extension

Drawing Exchange Format File

CAD Files

FLA file extension

Adobe Flash Animation

Developer Files

OTF file extension

OpenType Font

Font Files

AI file extension

Adobe Illustrator File

Vector Image Files

MOBI file extension

Mobipocket eBook

eBook Files

KMZ file extension

Google Earth Placemark File

GIS Files

ICNS file extension

Mac OS X Icon Resource File

System Files

7Z file extension

7-Zip Compressed File

Compressed Files

DOC file extension

Microsoft Word Document

Text Files