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

AI file extension

Adobe Illustrator File

Vector Image Files

CAB file extension

Windows Cabinet File

System Files

CFG file extension

Configuration File

Settings Files

CPL file extension

Windows Control Panel Item

System Files

DOC file extension

Microsoft Word Document

Text Files

EPUB file extension

Open eBook File

eBook Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

KMZ file extension

Google Earth Placemark File

GIS Files

PART file extension

Partially Downloaded File

Misc Files

PPS file extension

PowerPoint Slide Show

Data Files

RTF file extension

Rich Text Format File

Text Files

SYS file extension

Windows System File

System Files

UUE file extension

Uuencoded File

Encoded Files

WMA file extension

Windows Media Audio File

Audio Files

3G2 file extension

3GPP2 Multimedia File

Video Files