The ads on Facebook always seem to know exactly what I'm looking for. For example, I recently bought an iPhone 5 from AT&T. If you look at the accompanied image, you can see that my Facebook profile had advertisements for iPhone 5 cases as well as AT&T service along the side of my homepage this afternoon. It also has an advertisement for Minnesota apparel...I live in Minnesota. Coincidence? Not in this online marketing realm.
(OBA) is system that companies use to collect information about your online behavior. They take into account the websites that you visit most often and use that information to direct ads towards you that they think will interest you the most.
So the next time an ad pops up on your Facebook page about Rome while you're planning your trip to Europe, don't be too surprised.