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

DMG file extension

Mac OS X Disk Image

Disk Image Files

FLV file extension

Flash Video File

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

EPUB file extension

Open eBook File

eBook Files

VCD file extension

Virtual CD

Disk Image Files

DEB file extension

Debian Software Package

Compressed Files

WPD file extension

WordPerfect Document

Text Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

C file extension

C/C++ Source Code File

Developer Files

SYS file extension

Windows System File

System Files

CSS file extension

Cascading Style Sheet

Web Files

WSF file extension

Windows Script File

Executable Files

CSR file extension

Certificate Signing Request File

Web Files

PS file extension

PostScript File

Vector Image Files

CPP file extension

C++ Source Code File

Developer Files