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

APK file extension

Android Package File

Executable Files

CUR file extension

Windows Cursor

System Files

DDS file extension

DirectDraw Surface

Raster Image Files

DEM file extension

Video Game Demo File

Game Files

INDD file extension

Adobe InDesign Document

Layout Files

JAR file extension

Java Archive File

Executable Files

KML file extension

Keyhole Markup Language File

GIS Files

MOBI file extension

Mobipocket eBook

eBook Files

MOV file extension

Apple QuickTime Movie

Video Files

PART file extension

Partially Downloaded File

Misc Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SDF file extension

Standard Data File

Data Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

TEX file extension

LaTeX Source Document

Text Files

TMP file extension

Temporary File

Backup Files