Window vs view

I am new to WebDynpro and got a little confused about Windows/Views. The tutorials only show navigation among views. Where would I use multiple Windows?

Let's say an application has a login screen, some forms, and some list screens. Would I use only views (under only one window)?

If not, how would I navigate from window to window, since I can only connect plugs of views belonging to the same window. I guess I have missed something here.