ActiveX is a Microsoft web based plugin. It is Component Object Model (COM). Active X is a downloadable program that allow user to do many things.

ActiveX Features

1. Active X scripting is used in Microsoft internet Explorer to provide language-independent script handling capabilities 2. Active X documents supported by Active X means you can use the browser to view any Microsoft software application with that applications native toolbar, menu and other interface elements. This is also advantageous because you can use existing documents on the Internet without having to save them to HTML format.
3. Active X controls are the features that made this research interesting. These are actual software components embedded in web pages that run in the browser. If you visit a web page that uses, Microsoft’s Internet Explorer will automatically check to see if you have the needed control installed, if you do not, it installs it using their Authenticode.

Grab the extension from here.

To install it:

1. If you have Mozilla or NS 7.0 you may click to install it otherwise download it to disk (note this server might serve it as text/plain in which case shift click to save it straight to disk). This is an XPInstall file (a zip file with an .xpi extension).
2. If you downloaded the file, manually unzip the contents and copy npmozax.dll, nsIMozAxPlugin.xpt and MozAxPlugin.class into your plug-ins folder, e.g. “c:\program files\Netscape\Program\plugins”.
3. If necessary copy the msvcrt.dll & msvcp60.dll to your windows system folder (system32 for 2000/XP/NT systems)
4. Restart Mozilla/Netscape and verify that the plug-in has been detected by browsing to the URL about:plugins. The Mozilla plug-in should be listed.
5. Try testing the plug-in here with the Microsoft calendar control.

Credits
Mozilla ActiveX Control
C# Corner Pros and Cons of ActiveX and DHTML Controls

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