Google
The amount of information the giant Google, amasses must be colossal, with tracking on your Adsense account, and Google analytics, and Pay-per-click. And also for the average member of public, they can view which are the most popular searches and search terms and which websites you have viewed and for how long.
They have huge control over the vast worldwide web and can make campaigns very expensive for the newbie, as we all occasionally make mistakes as I  have found out to my cost. Some keywords are far too expensive to consider when first starting out. Keeping track on expenses is vital, especially if like me you were not getting any returns, although the number of hits vastly increased with the extra advertising. It is quite interesting seeing where your visitors have come from and from which countries. Showing it is truly a worldwide web.
The information in these accounts is at times baffling to the inexperienced beginner. And knowing how to use this information to put yourself in a better position, for increased sales is a must.  But in your quest for sales and visibility on the web don’t forget the other search engines such as Yahoo, Msm and all the other smaller ones as added together they can equal the number of searches as on google.