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

WSF file extension

Windows Script File

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

CLASS file extension

Java Class File

Developer Files

AIF file extension

Audio Interchange File Format

Audio Files

PY file extension

Python Script

Developer Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

DMP file extension

Windows Memory Dump

System Files

PIF file extension

Program Information File

Executable Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

DAT file extension

Data File

Data Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

CSS file extension

Cascading Style Sheet

Web Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files