Google is keeping an eye on what people buy at brick-and-mortar stores in a bid to measure how successful digital advertising campaigns are.
A new feature, born out of partnerships between Google and credit and debit card companies, links in-store purchases to your online identity, CNN reports. That means Google could tell whether you clicked an online ad before buying the product in a shop later.
Companies that Google partners reportedly account for 70% of all credit and debit card purchases in the U.S. According to CNN, credit and debit card companies will send Google encrypted information about store purchases, that can then be compared to collective online profiles of users who clicked on corresponding ads.
Google said that encryption means it cannot see identifiable payment information such as the customer's name or what they bought. The tool also doesn't work for cash payments.
By matching the ad clicks with in-store data, Google can tell advertisers how much real life business their online ads bring in.
Fore more about Google, watch Fortune's video:
Google's parent company Alphabet made $21.4 billion in ad sales last quarter and Google is expected to bring in about $73.8 billion in ad revenue this year.