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

ASP file extension

Active Server Page

Web Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

DMP file extension

Windows Memory Dump

System Files

DRV file extension

Device Driver

System Files

GADGET file extension

Windows Gadget

Executable Files

JAR file extension

Java Archive File

Executable Files

MAX file extension

3ds Max Scene File

3D Image Files

MOV file extension

Apple QuickTime Movie

Video Files

PNG file extension

Portable Network Graphic

Raster Image Files

SITX file extension

StuffIt X Archive

Compressed Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

SYS file extension

Windows System File

System Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files

3DS file extension

3D Studio Scene

3D Image Files