Like most websites Google keeps a log of IP addresses in order to track visitor behavior, and to help serve up more useful ad targeting. Previously they held onto this non-identifying information for 18 months following your visit to their site.
Over the past couple of years regulators and policymakers have had privacy concerns over the storage of this data, and as a result Google has cut the time it holds onto this information by half, down to 9 months.
Peter Fleischer, Google’s global privacy counsel was noted as saying:
“Finding the right balance between data retention and privacy is a tough issue for policymakers, Google and our industry. There is great utility in data, but we also believe that limiting the amount and types of data we keep can improve privacy while continuing to provide a strong user experience. Anonymizing the data earlier will have costs, particularly in terms of future search quality improvements. But our engineers are working hard to minimize those losses.”