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

ODT file extension

OpenDocument Text Document

Text Files

AVI file extension

Audio Video Interleave File

Video Files

FLV file extension

Flash Video File

Video Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

VOB file extension

DVD Video Object File

Video Files

AI file extension

Adobe Illustrator File

Vector Image Files

DXF file extension

Drawing Exchange Format File

CAD Files

PPS file extension

PowerPoint Slide Show

Data Files

AZW file extension

Amazon Kindle eBook File

eBook Files

CFM file extension

ColdFusion Markup File

Web Files

3DM file extension

Rhino 3D Model

3D Image Files

CPP file extension

C++ Source Code File

Developer Files

ASP file extension

Active Server Page

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files