ActiveX Controls are downloadable software components that are used to extend the functionality of Internet Explorer through user-interface elements such as pop-up menus, buttons, and so on.

Active scripting is a Microsoft technology that allows different software components to interact with one another in a networked environment (in this case, the Internet), regardless of the language in which the components were created. Active scripting is what allows Web pages to use animation and to change their content dynamically.

Although most active content contained in Web pages is safe, some Web pages might contain active content that could cause security problems on your computer. Internet Explorer uses safety levels for active content to help prevent security issues from occurring. For more information, read the Microsoft Knowledge Base Article about Internet Explorer security settings.

While browsing the Web, you are protected from downloading unwanted ActiveX Controls because when a Web page attempts to download one, Internet Explorer presents you with a signed certificate displaying the control's publisher. This certificate appears as a Security Warning dialog box. If you are on a Web site that you trust (in this case, Windows Update), and the ActiveX Control is provided by a publisher you trust (in this case, Microsoft), it is safe to click Yes in the dialog box to accept the certificate and allow the control to be installed.