Google is phasing out support for third-party cookies within two years, a move that has major implications for how some retailers advertise — and may also be a boon for retail media operations at major companies like Target and Walmart.

Third-party cookies are pieces of code that track what a user or their device does across different websites, and help retailers figure out when to serve an ad to various groups of users.

They’re most commonly used for ad retargeting and behavioral advertising. As such, as Google prepares to phase out support for third-party cookies, it could limit the number of ways retailers can target and advertise to users across the web.