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

IFF file extension

Interchange File Format

Audio Files

MOV file extension

Apple QuickTime Movie

Video Files

PDF file extension

Portable Document Format File

Layout Files

SAV file extension

Saved Game

Game Files

7Z file extension

7-Zip Compressed File

Compressed Files

BMP file extension

Bitmap Image File

Raster Image Files

BAT file extension

DOS Batch File

Executable Files

PRF file extension

Outlook Profile File

Settings Files

PCT file extension

Picture File

Layout Files

ZIPX file extension

Extended Zip File

Compressed Files

RA file extension

Real Audio File

Audio Files

VCD file extension

Virtual CD

Disk Image Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

CPP file extension

C++ Source Code File

Developer Files

DMG file extension

Mac OS X Disk Image

Disk Image Files