Basically what this means is that if you have a Gmail account, whenever you do a search for something in regular google search or youtube, it will track and record everything you do if your still logged in. The finest example is YouTube. I've went from YouTube (while in my email) and noticed that Google had me logged in YouTube under my email account. Honestly, that really pisses me off because I did not log into YouTube by choice and do not want them logging me into YouTube without my permission. I basically have to log out of that google account just to log into the YouTube account I originally created before google bought YouTube.