Now this is powerfull you can view what you have done on google. its like a flashback of your life not entier though only to the one that is related to google. Here you can view here have you went, checked in, searched and what you have seen on youtube. The bright side is google can predict your intrests and behavior and predict your next intrest which could save you alot of time. In the worng hands this could be a perfect for social engineering attacks. Google can use this data to improve services to the general population and also give you a more controlled and personalized experiance. Check out thier Privacy page.