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

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

IBOOKS file extension

Multi-Touch iBook

Data Files

WAV file extension

WAVE Audio File

Audio Files

BMP file extension

Bitmap Image File

Raster Image Files

TXT file extension

Plain Text File

Text Files

ASX file extension

Microsoft ASF Redirector File

Video Files

H file extension

C/C++/Objective-C Header File

Developer Files

PNG file extension

Portable Network Graphic

Raster Image Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

PIF file extension

Program Information File

Executable Files

LOG file extension

Log File

Text Files

7Z file extension

7-Zip Compressed File

Compressed Files

VCXPROJ file extension

Visual C++ Project

Developer Files