Restrict apps from accessing the internet at the background without the end-user knowledge Is it possible to restrict app from accessing the internet at the background without the end-user knowledge. (Assume the phone is not rooted)

In other word, are there apps that can inform the end-user that some apps is trying to access the internet at the background?
I think you'd require root for this sort of functionality. If you have ICS and later on your device, you can check the data usage and identify apps. Go to SETTINGS > DATA USAGE.

A list of apps and the data that they've consumed should be displayed there. That will allow you to see which apps have accessed the mobile data connection.

Screenshots here - http://www.tech-recipes.com/rx/22583/android-ics-control-limit-data-usage/