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

COM file extension

DOS Command File

Executable Files

DBF file extension

Database File

Database Files

FON file extension

Generic Font File

Font Files

GADGET file extension

Windows Gadget

Executable Files

KMZ file extension

Google Earth Placemark File

GIS Files

OTF file extension

OpenType Font

Font Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SDF file extension

Standard Data File

Data Files

SLN file extension

Visual Studio Solution File

Developer Files

UUE file extension

Uuencoded File

Encoded Files

WAV file extension

WAVE Audio File

Audio Files

WSF file extension

Windows Script File

Executable Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files