Online shopper Mario Almonte was shocked the first time he surfed the Web for a certain product and then saw an ad for the very same thing pop up on a different website.
"I suddenly felt like I was being followed, like you're in a dark alley," said Almonte.
Experts say he's right. Consumers are quietly being followed, even targeted, when they browse online. One specialized software lets you see for yourself how you're being tracked while you surf the Web.
"That's all being stored and sold and shared among hundreds of different companies," said Sarah Downey, an attorney and privacy expert.
The Federal Trade Commission is pushing to give consumers greater control by creating a "Do Not Track" system. The goal is to allow you to opt out with the click of a button. The problem is, right now, what "Do Not Track" means is still being debated.
"What the FTC has said is that 'Do Not Track' should mean that information about where you go on the net is not collected by third parties, with narrow exceptions for things like ensuring security," said Dr. Edward Felten of the FTC.
But the FTC says some digital companies want "Do Not Track" to mean consumers can just "opt out" of receiving targeted ads, but not out of data collection.
"If your business model depends on tracking people online, then obviously you'd like that to be able to continue," said Felten.
The Direct Marketing Association responds that it has to collect some anonymous data to help improve how the Web works and also use it for analytics and market research.
"That's not for targeting. It's for if you're a rent-a-car company, and you're getting a lot of clicks from a particular area, you might want to open up a new rental car agency in that area," said Linda Wolley of the Direct Marketing Association.
The Digital Advertising Alliance (DAA) recently unveiled its "self-regulated" opt-out program. You just click on a little icon on behaviorally-targeted ads and you can choose not to get them. But before you do that, keep in mind you'll still see ads, just not for items you may have searched recently.
Almonte is giving it a try because until it's all figured out, he sees it as one way to try and protect his privacy.