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

MSI file extension

Windows Installer Package

Misc Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

RPM file extension

Red Hat Package Manager File

Compressed Files

DDS file extension

DirectDraw Surface

Raster Image Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

COM file extension

DOS Command File

Executable Files

JSP file extension

Java Server Page

Web Files

JS file extension

JavaScript File

Web Files

JPG file extension

JPEG Image

Raster Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

ICNS file extension

Mac OS X Icon Resource File

System Files

TARGZ file extension

Compressed Tarball File

Compressed Files

LOG file extension

Log File

Text Files

7Z file extension

7-Zip Compressed File

Compressed Files

ROM file extension

N64 Game ROM File

Game Files