Google to overhaul ad tracking system on Android devices

Google announced plans Wednesday to limit ad tracking on its Android operating system running on billions of devices, a sensitive privacy issue that rival Apple has already moved to address on its iPhones.

Tech giants are under growing pressure to better balance privacy and ad-targeting, as users complain and regulators threaten tougher rules -- but the companies themselves try to maintain access to the precious data helping them earn billions in ad revenue.