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

RSS file extension

Rich Site Summary

Web Files

DDS file extension

DirectDraw Surface

Raster Image Files

EPUB file extension

Open eBook File

eBook Files

MPA file extension

MPEG-2 Audio File

Audio Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

MDB file extension

Microsoft Access Database

Database Files

WSF file extension

Windows Script File

Executable Files

MSI file extension

Windows Installer Package

Misc Files

KEY file extension

Keynote Presentation

Data Files

AIF file extension

Audio Interchange File Format

Audio Files

INDD file extension

Adobe InDesign Document

Layout Files

ACCDB file extension

Access 2007 Database File

Database Files

SWF file extension

Shockwave Flash Movie

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

JAVA file extension

Java Source Code File

Developer Files