ActiveX is a set of object-oriented programming technologies and tools that Microsoft developed for Internet Explorer to facilitate rich media playback.
Essentially, Internet Explorer uses the ActiveX software framework to load other applications in the browser. ActiveX modules are more commonly known as controls or ActiveX controls. ActiveX controls, which are somewhat similar to Java applets, extend a browser's functionality, allowing it to perform tasks it would otherwise not be capable of doing natively. An ActiveX plug-in allows a browser to take advantage of these capabilities.
What is ActiveX used for?
ActiveX controls can serve a wide variety of purposes. For example, ActiveX controls were used early on to allow users to play videos and other multimedia content directly through the browser without having to open a media player. Users could also work with ActiveX to view PDF files through the browser or to support Flash animations.
ActiveX controls are designed to be reusable. As such, a developer building a website did not necessarily have to create his own ActiveX controls. In many cases, it was possible for web developers to enable functionality by using pre-existing ActiveX controls, such as those used for playing multimedia files.
Because some ActiveX controls are so prevalent, attackers began to look for ways to exploit vulnerabilities within common ActiveX controls. In addition, attackers began building malicious ActiveX controls.
Because malicious use of ActiveX controls became such a widespread problem, Microsoft designed Internet Explorer 7 to display a warning every time a site attempts to use an ActiveX control. It's up to the user to decide whether or not the request comes from a trustworthy source. Today, ActiveX controls are far less common than they once were because so many browsers either disable ActiveX controls by default or do not support them at all.
Google Chrome support
Google Chrome does not natively support ActiveX, but it is possible to add ActiveX Chrome support through the use of a browser extension. To do so, open Chrome, and go to More Tools > Extensions. This opens the Chrome Web Store. Use the search engine to look for an extension called IE Tab. Add the extension to the browser.
Once the browser extension is in place, a small IE icon will appear just to the right of Chrome's address bar. Click on this button to open the IE Tab configuration page. This page prompts the user to download and run a file named IETabHelper.exe. Upon doing so, ActiveX Chrome support is in place, so the user can access Internet Explorer content, such as ActiveX controls, through Chrome's IE tab.
Microsoft browser support
The Microsoft Edge browser in Windows 10 does not support the use of ActiveX controls. Internet Explorer 11, which is also included with Windows 10, continues to support ActiveX controls, however. Even so, much of the ActiveX functionality is disabled by default.
It is possible to adjust Internet Explorer's support for ActiveX by clicking on the Tools button and choosing Internet Options. Upon doing so, the browser will display the Internet Options dialog box. Go to the dialog box's Security tab, and click the Custom Level button. This opens a Security Settings dialog box, which contains all of the browser's ActiveX related settings.