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

AIF file extension

Audio Interchange File Format

Audio Files

ASPX file extension

Active Server Page Extended File

Web Files

DXF file extension

Drawing Exchange Format File

CAD Files

IBOOKS file extension

Multi-Touch iBook

Data Files

JAVA file extension

Java Source Code File

Developer Files

JSP file extension

Java Server Page

Web Files

PY file extension

Python Script

Developer Files

RA file extension

Real Audio File

Audio Files

SYS file extension

Windows System File

System Files

TXT file extension

Plain Text File

Text Files

VCF file extension

vCard File

Data Files

VOB file extension

DVD Video Object File

Video Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files

3DM file extension

Rhino 3D Model

3D Image Files