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

TIF file extension

Tagged Image File

Raster Image Files

SQL file extension

Structured Query Language Data File

Database Files

PDF file extension

Portable Document Format File

Layout Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

BAK file extension

Backup File

Backup Files

AZW file extension

Amazon Kindle eBook File

eBook Files

INDD file extension

Adobe InDesign Document

Layout Files

7Z file extension

7-Zip Compressed File

Compressed Files

MID file extension

MIDI File

Audio Files

PPT file extension

PowerPoint Presentation

Data Files

MOV file extension

Apple QuickTime Movie

Video Files

VCF file extension

vCard File

Data Files

PCT file extension

Picture File

Layout Files

PKG file extension

Mac OS X Installer Package

Compressed Files

IBOOKS file extension

Multi-Touch iBook

Data Files