Google explains the reason of keeping the logs of every query and activity we are doing with Google.
From the article:
“We recently announced a new policy to anonymize our server logs after 18–24 months. We’re the only leading search company to have taken this step publicly. We believe it’s an important part of our commitment to respect user privacy while balancing a number of important factors.
In developing this policy, we spoke with various privacy advocates, regulators and others about how long they think the period should be. There is a wide spectrum of views on this – some think data should be preserved for longer, others think it should be anonymized almost immediately. We spent a great deal of time sorting this out and thought we’d explain some of the things that prompted us to decide on 18-24 months.
Three factors were critical. One was maintaining our ability to continue to improve the quality of our search services. Another was to protect our systems and our users from fraud and abuse. The third was complying—and anticipating compliance—with possible data retention requirements. Here’s a bit more about each of these:…” read more