ActiveX is briefly described here click here and here click here. In Internet Explorer, to enable ActiveX, click on Tools - Internet Options - Security - Custom level. In my system the following are selected.
Download signed ActiveX controls - Prompt.
Download unsigned ActiveX controls - Disable.
Initialise and script ActiveX controls not marked as safe - Disable.
Run ActiveX controls and plug-ins - Enable
Script ActiveX controls marked safe for scripting - Enable