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

KMZ file extension

Google Earth Placemark File

GIS Files

PKG file extension

Mac OS X Installer Package

Compressed Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

DXF file extension

Drawing Exchange Format File

CAD Files

7Z file extension

7-Zip Compressed File

Compressed Files

EPUB file extension

Open eBook File

eBook Files

RM file extension

Real Media File

Video Files

TXT file extension

Plain Text File

Text Files

PHP file extension

PHP Source Code File

Web Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

3GP file extension

3GPP Multimedia File

Video Files

GADGET file extension

Windows Gadget

Executable Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

VCD file extension

Virtual CD

Disk Image Files