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

ASPX file extension

Active Server Page Extended File

Web Files

AZW file extension

Amazon Kindle eBook File

eBook Files

CFG file extension

Configuration File

Settings Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

EPUB file extension

Open eBook File

eBook Files

JAVA file extension

Java Source Code File

Developer Files

LNK file extension

Windows File Shortcut

System Files

ODT file extension

OpenDocument Text Document

Text Files

PCT file extension

Picture File

Layout Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SYS file extension

Windows System File

System Files

TTF file extension

TrueType Font

Font Files

WPS file extension

Microsoft Works Word Processor Document

Text Files