Gregory's ServerActually a browser could do that, too since they represent that you are entering a URL and get a page displayed. But a “browser” could also be transmitting just the URL to some cloud machine which will do everything for you and then the “browser” on your machine displays the page and everything. Bit nobody did it so far. (3/4)
I guess Outlook New is just a glorified webmailer (and from what I've read it is a chromium wrapper) which looks like a local app. That would also explain why it won't start when you are offline. (4/4)