ActiveX is a collection of technologies, protocols, and APIs developed by Microsoft that are used for automatically downloading executable machine code over the Internet. The code is bundled into a single file called an ActiveX control and the file has the extension OCX. You can think of an ActiveX control as a self-installing plug-in.
ActiveX controls are automatically downloaded when Internet Explorer encounters a web page containing an <OBJECT> tag that references an ActiveX control. Depending on the current setting for Internet Explorer, these tags either are ignored or cause software to be downloaded. If the control is downloaded (again depending on the security setting of Internet Explorer), the control may be run directly, or the user may be prompted as to whether the control should or should not be run. This process is shown in Figure 12-4.
Figure 12-4. Internet Explorer’s security settings determine whether ActiveX controls will be downloaded and how they will be run.
ActiveX is an extraordinarily powerful technology. Because raw machine code is downloaded and run, the ActiveX controls can do anything—from displaying a new file type to upgrading your computer’s operating system!
Despite the similarities between ActiveX controls and plug-ins, there are a few significant differences:
ActiveX applets have been used for much more than plug-ins. Whereas plug-ins ...