Windows 8 Metro Style app development starts with choosing a user interface technology path. Developers will need to choose whether they will create their user interface using XAML or HTML5. Choosing XAML means that the business logic for the application can be implemented using C++, C#, or VB. HTML5 apps will mainly use JavaScript for this purpose (note: it is possible to call into C++/C#/VB code in an HTML5 app).