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

3DS file extension

3D Studio Scene

3D Image Files

KML file extension

Keyhole Markup Language File

GIS Files

PIF file extension

Program Information File

Executable Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

PCT file extension

Picture File

Layout Files

7Z file extension

7-Zip Compressed File

Compressed Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

SITX file extension

StuffIt X Archive

Compressed Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

PHP file extension

PHP Source Code File

Web Files

PDB file extension

Program Database

Database Files

LNK file extension

Windows File Shortcut

System Files

APK file extension

Android Package File

Executable Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CFG file extension

Configuration File

Settings Files