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

AI file extension

Adobe Illustrator File

Vector Image Files

SWF file extension

Shockwave Flash Movie

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

PIF file extension

Program Information File

Executable Files

DOC# file extension

Microsoft Word Document

Text Files

H file extension

C/C++/Objective-C Header File

Developer Files

MDF file extension

Media Disc Image File

Disk Image Files

ZIP file extension

Zipped File

Compressed Files

INI file extension

Windows Initialization File

Settings Files

PHP file extension

PHP Source Code File

Web Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

TTF file extension

TrueType Font

Font Files

DAT file extension

Data File

Data Files

SITX file extension

StuffIt X Archive

Compressed Files

VCF file extension

vCard File

Data Files