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

ASX file extension

Microsoft ASF Redirector File

Video Files

CAB file extension

Windows Cabinet File

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

INDD file extension

Adobe InDesign Document

Layout Files

JAVA file extension

Java Source Code File

Developer Files

KEY file extension

Keynote Presentation

Data Files

LUA file extension

Lua Source File

Developer Files

M4V file extension

iTunes Video File

Video Files

OTF file extension

OpenType Font

Font Files

PPS file extension

PowerPoint Slide Show

Data Files

TEX file extension

LaTeX Source Document

Text Files

TXT file extension

Plain Text File

Text Files

UUE file extension

Uuencoded File

Encoded Files

WPS file extension

Microsoft Works Word Processor Document

Text Files