The WebBrowser control is primarily a managed wrapper of the WebBrowser ActiveX object. There are four main unmanaged interfaces that are wrapped in one form or another:

1. IWebBrowser2 – The core WebBrowser interface.
2. DWebBrowserEvents2 – The WebBrowser events.
3. IDocHostUIHandler – Provides advanced functionality such as: custom context menus, disabling accelerators & providing custom objects to the html script. The WebBrowser control QI's it's Site to obtain this interface.
4. IinternetSecurityManager – Provides custom security for the browser control. The WebBrowser control QI's it's Site to obtain this interface.