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

AIF file extension

Audio Interchange File Format

Audio Files

APP file extension

Mac OS X Application

Executable Files

DDS file extension

DirectDraw Surface

Raster Image Files

EPUB file extension

Open eBook File

eBook Files

GADGET file extension

Windows Gadget

Executable Files

INI file extension

Windows Initialization File

Settings Files

ISO file extension

Disc Image File

Disk Image Files

JAR file extension

Java Archive File

Executable Files

PCT file extension

Picture File

Layout Files

PNG file extension

Portable Network Graphic

Raster Image Files

PY file extension

Python Script

Developer Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SWF file extension

Shockwave Flash Movie

Video Files

TMP file extension

Temporary File

Backup Files

XML file extension

XML File

Data Files