You’ve probably had this experience: You go online to research a purchase—like a riding lawnmower—and click around some manufacturer and retail sites. Within an hour, ads for riding lawnmowers start turning up on every website and mobile app you use. The blitz continues for days.
John Bruno can relate. The vice president of commerce strategy at e-commerce technology firm PROS remembers that when he went shopping for an engagement ring a few years ago, “I had to hide every device I own,” so a wayward ad wouldn’t tip off his wife-to-be.
This little bit of creepiness is brought to you by cookies, those little unassuming files buried so deep in the guts of our computers that most people wouldn’t even know where to find them. Web servers know where to look, though, and the information contained within them is what enables advertisers to follow you around like a stalker.