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

7Z file extension

7-Zip Compressed File

Compressed Files

SYS file extension

Windows System File

System Files

ICS file extension

iCalendar File

Misc Files

INI file extension

Windows Initialization File

Settings Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

MDF file extension

Media Disc Image File

Disk Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

H file extension

C/C++/Objective-C Header File

Developer Files

TEX file extension

LaTeX Source Document

Text Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

MP4 file extension

MPEG-4 Video File

Video Files

KML file extension

Keyhole Markup Language File

GIS Files

PDF file extension

Portable Document Format File

Layout Files

DOC file extension

Microsoft Word Document

Text Files

DEB file extension

Debian Software Package

Compressed Files