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

APP file extension

Mac OS X Application

Executable Files

AZW file extension

Amazon Kindle eBook File

eBook Files

BIN file extension

Binary Disc Image

Disk Image Files

C file extension

C/C++ Source Code File

Developer Files

CSS file extension

Cascading Style Sheet

Web Files

DMP file extension

Windows Memory Dump

System Files

EPUB file extension

Open eBook File

eBook Files

GPX file extension

GPS Exchange File

GIS Files

ICO file extension

Icon File

System Files

MOV file extension

Apple QuickTime Movie

Video Files

MPA file extension

MPEG-2 Audio File

Audio Files

PAGES file extension

Pages Document

Text Files

PCT file extension

Picture File

Layout Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

UUE file extension

Uuencoded File

Encoded Files