When we are on facebook page and someone sends us a message,(not chat message), or any notification does occurs, Then a red number is appeared at the top to notify us (user) about the message. even if we don't refresh the page. This happens without the page refresh,
Same thing does occur when some one posts new tweets on twitter, page is not refreshed and tweets appears automatically.
Does anyone know how to do this? Any example or tutorial on related topic will really be helpful.
Many Thanks in advance