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

ASPX file extension

Active Server Page Extended File

Web Files

EPUB file extension

Open eBook File

eBook Files

INDD file extension

Adobe InDesign Document

Layout Files

JAVA file extension

Java Source Code File

Developer Files

KMZ file extension

Google Earth Placemark File

GIS Files

MAX file extension

3ds Max Scene File

3D Image Files

PART file extension

Partially Downloaded File

Misc Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SYS file extension

Windows System File

System Files

TIF file extension

Tagged Image File

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

WMV file extension

Windows Media Video File

Video Files

3DM file extension

Rhino 3D Model

3D Image Files

3GP file extension

3GPP Multimedia File

Video Files