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

CUR file extension

Windows Cursor

System Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

EPUB file extension

Open eBook File

eBook Files

GPX file extension

GPS Exchange File

GIS Files

INDD file extension

Adobe InDesign Document

Layout Files

ISO file extension

Disc Image File

Disk Image Files

JAR file extension

Java Archive File

Executable Files

MSG file extension

Outlook Mail Message

Text Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

OTF file extension

OpenType Font

Font Files

TAR file extension

Consolidated Unix File Archive

Data Files

TIF file extension

Tagged Image File

Raster Image Files

TOAST file extension

Toast Disc Image

Disk Image Files

VB file extension

VBScript File

Executable Files

3DS file extension

3D Studio Scene

3D Image Files