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

AZW file extension

Amazon Kindle eBook File

eBook Files

CER file extension

Internet Security Certificate

Web Files

COM file extension

DOS Command File

Executable Files

DOC file extension

Microsoft Word Document

Text Files

DXF file extension

Drawing Exchange Format File

CAD Files

EXE file extension

Windows Executable File

Executable Files

FLA file extension

Adobe Flash Animation

Developer Files

JS file extension

JavaScript File

Web Files

KEY file extension

Keynote Presentation

Data Files

MPG file extension

MPEG Video File

Video Files

PRF file extension

Outlook Profile File

Settings Files

SDF file extension

Standard Data File

Data Files

SWF file extension

Shockwave Flash Movie

Video Files

THM file extension

Thumbnail Image File

Raster Image Files

VCXPROJ file extension

Visual C++ Project

Developer Files