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

7Z file extension

7-Zip Compressed File

Compressed Files

DMP file extension

Windows Memory Dump

System Files

RA file extension

Real Audio File

Audio Files

PART file extension

Partially Downloaded File

Misc Files

3DS file extension

3D Studio Scene

3D Image Files

TGA file extension

Targa Graphic

Raster Image Files

JAR file extension

Java Archive File

Executable Files

COM file extension

DOS Command File

Executable Files

ICNS file extension

Mac OS X Icon Resource File

System Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

VCD file extension

Virtual CD

Disk Image Files

RM file extension

Real Media File

Video Files

MSI file extension

Windows Installer Package

Misc Files