This allows you to put a Web browser into your WPF application.
A key point to note, which is not obvious from the documentation, and you could go for years without knowing is that it defaults to behaving like InternetExplorer7, rather than your most up-to-date InternetExplorer installation (see https://weblog.west-wind.com/posts/2011/may/21/web-browser-control-specifying-the-ie-version ).
This cannot be fixed by setting a property on the control; you must either modify the pages being displayed by adding an HTML Meta Tag, or by applying a registry setting(!). (Details of both approaches are on the link above.)
For example, this bizarre design behaviour might lead you to get a message saying "Script Error"/"An error has occurred in the script on this page". Googling this error might make you think that the solution is to try to suppress the error, rather that understanding the actual problem, and applying the correct solution.