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

ACCDB file extension

Access 2007 Database File

Database Files

APK file extension

Android Package File

Executable Files

ASX file extension

Microsoft ASF Redirector File

Video Files

DB file extension

Database File

Database Files

FON file extension

Generic Font File

Font Files

GED file extension

GEDCOM Genealogy Data File

Data Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

JS file extension

JavaScript File

Web Files

JSP file extension

Java Server Page

Web Files

KEY file extension

Keynote Presentation

Data Files

PKG file extension

Mac OS X Installer Package

Compressed Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

VCXPROJ file extension

Visual C++ Project

Developer Files

WSF file extension

Windows Script File

Executable Files

XLR file extension

Works Spreadsheet

Spreadsheet Files