Google collects extensive data on users' online activities through services like Gmail, Google Search, YouTube, and more. This data includes email content, search histories, videos watched, and other online behaviors. Google uses this data to personalize services for users and enable targeted advertising. While users retain ownership of their content, by agreeing to Google's terms of service users give Google broad rights to use their data. Google collects data through technologies like cookies, IP addresses, and server logs that allow tracking of users' activities and interests over time.