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

CSS file extension

Cascading Style Sheet

Web Files

TAR file extension

Consolidated Unix File Archive

Data Files

CSR file extension

Certificate Signing Request File

Web Files

FLV file extension

Flash Video File

Video Files

KML file extension

Keyhole Markup Language File

GIS Files

ACCDB file extension

Access 2007 Database File

Database Files

SYS file extension

Windows System File

System Files

RA file extension

Real Audio File

Audio Files

DRV file extension

Device Driver

System Files

DLL file extension

Dynamic Link Library

System Files

7Z file extension

7-Zip Compressed File

Compressed Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

GED file extension

GEDCOM Genealogy Data File

Data Files

SWF file extension

Shockwave Flash Movie

Video Files

TIFF file extension

Tagged Image File Format

Raster Image Files