Google track every move you left on the internet. Which websites you are visiting, which products you checked, which kind of behavior you have online (meaning your characteristic analysis) 

With these all analysis Google might even know you better than you do. 

Some of you might not make this issue a serious problem and do not care.

However, if you care not to give your private data to Google, you should take some precautions like using DuckDuckGo. This search engine does not keep your data and does not make any relation your data and your identity. 

If you care your privacy, you could use DuckDuckGo instead of Google. I hope this helps.