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

BAT file extension

DOS Batch File

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

BIN file extension

Binary Disc Image

Disk Image Files

SWF file extension

Shockwave Flash Movie

Video Files

AI file extension

Adobe Illustrator File

Vector Image Files

IBOOKS file extension

Multi-Touch iBook

Data Files

PL file extension

Perl Script

Developer Files

GBR file extension

Gerber File

Data Files

NES file extension

Nintendo (NES) ROM File

Game Files

INDD file extension

Adobe InDesign Document

Layout Files

MP3 file extension

MP3 Audio File

Audio Files

FNT file extension

Windows Font File

Font Files

WMA file extension

Windows Media Audio File

Audio Files

DTD file extension

Document Type Definition File

Developer Files