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

DMG file extension

Mac OS X Disk Image

Disk Image Files

FON file extension

Generic Font File

Font Files

ISO file extension

Disc Image File

Disk Image Files

JS file extension

JavaScript File

Web Files

KML file extension

Keyhole Markup Language File

GIS Files

MOBI file extension

Mobipocket eBook

eBook Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PHP file extension

PHP Source Code File

Web Files

RPM file extension

Red Hat Package Manager File

Compressed Files

TIFF file extension

Tagged Image File Format

Raster Image Files

VCF file extension

vCard File

Data Files

WSF file extension

Windows Script File

Executable Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

ZIP file extension

Zipped File

Compressed Files