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

CSR file extension

Certificate Signing Request File

Web Files

GED file extension

GEDCOM Genealogy Data File

Data Files

MPG file extension

MPEG Video File

Video Files

PART file extension

Partially Downloaded File

Misc Files

PIF file extension

Program Information File

Executable Files

PKG file extension

Mac OS X Installer Package

Compressed Files

RSS file extension

Rich Site Summary

Web Files

SITX file extension

StuffIt X Archive

Compressed Files

SYS file extension

Windows System File

System Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TIF file extension

Tagged Image File

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

VOB file extension

DVD Video Object File

Video Files

WSF file extension

Windows Script File

Executable Files

YUV file extension

YUV Encoded Image File

Raster Image Files