Every search engine gathers information about its users—primarily by sending us “cookies,” or text files that track our online movements. Most cookies expire within a few months or years. Google’s, though, don’t expire until 2038. Until then, when you use the company’s search engine or visit any of myriad affiliated sites, it will record what you search for and when, which links you click on, which ads you access. Google’s cookies can’t identify you by name, but they log your computer’s IP address; by way of metaphor, Google doesn’t have your driver’s license number, but it knows the license plate number of the car you are driving. And search queries are windows into our souls, as 658,000 aol users learned when their search profiles were mistakenly posted on the Internet: Would user 1997374 have searched for information on better erections or cunnilingus if he’d known that aol was recording every keystroke? Would user 22155378 have keyed in “marijuana detox” over and over knowing someone could play it all back for the world to see? If you’ve ever been seized by a morbid curiosity after a night of hard drinking, a search engine knows—and chances are it’s Google, which owns roughly half of the entire search market and processes more than 3 billion queries a month.