Google starts tracking your offline shopping -- what you buy at stores, in person

Google already monitors your online shopping -- but now it's also keeping an eye on what you're buying in real-world stores as part of its latest effort to sell more digital advertising. The offline tracking scans most credit and debit card transactions to help Google automatically inform merchants when their digital ads translate into sales at a brick-and-mortar store. Google believes the data will show a cause-and-effect relationship between online ads and offline sales. If it works, that could help persuade merchants to boost their digital marketing budgets. The Mountain View, Calif., company -- a division of Alphabet Inc. -- already runs the world's biggest online ad network, one that raked in $79 billion in revenue last year.