Our REST Web Service will sit on a Server "somewhere" our Angular
		client will sit on a user Browser "somewhere else"
		
		
		so all call to the Web Service are Asynchronous  !!!! IMPORTENT
		
		the call may take a while
		
		so Angular has a "Callback" feature to update your code (the component)
		when the results are back
		
		this is an Observable (older version of Angular used Promises) 
		
		My code will subscribe to the Observable, this means my code will run
		when the HTTP call completes