@yours.mukul Heh. All right, short version:
When a module starts up (as directed by the main application), that module returns a chunk of HTML code that the application will then render and place upon the interface. If the module needs information from another source (RSS feed, weather information, sports scores, whatever), the application framework has hooks that allow a node process to retrieve/generate that information and then present it to front-end module code. Any state information is stored in memory and is regularly replaced by the back end process.
I hope that clarifies things.