Open your phone and find an appl
        you use often
        
        your are looking at the Front-End
        can you find where/who provides the Back-End
        
        is this app small? a single server on the Back-End
        is the app large? a set of servers...
        
        what you see is a new trend in Appl development
        Single Page Application
        
        where the front end is on your device
        and consists on a single page
        
        the back-end is a Web Service (send/receive data)
        on the cloud