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

BIN file extension

Binary Disc Image

Disk Image Files

DBF file extension

Database File

Database Files

DMP file extension

Windows Memory Dump

System Files

GBR file extension

Gerber File

Data Files

KEY file extension

Keynote Presentation

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

MSI file extension

Windows Installer Package

Misc Files

PCT file extension

Picture File

Layout Files

PHP file extension

PHP Source Code File

Web Files

PRF file extension

Outlook Profile File

Settings Files

RM file extension

Real Media File

Video Files

SDF file extension

Standard Data File

Data Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3DS file extension

3D Studio Scene

3D Image Files