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

XLR file extension

Works Spreadsheet

Spreadsheet Files

VCF file extension

vCard File

Data Files

BAK file extension

Backup File

Backup Files

VOB file extension

DVD Video Object File

Video Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

THM file extension

Thumbnail Image File

Raster Image Files

ZIP file extension

Zipped File

Compressed Files

BIN file extension

Binary Disc Image

Disk Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

KEY file extension

Keynote Presentation

Data Files

SDF file extension

Standard Data File

Data Files

GBR file extension

Gerber File

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

GPX file extension

GPS Exchange File

GIS Files