Transcript for What do Google and Facebook know about you?
We're going to turn to that "Gma" consumer alert. Are internet megacompanies stalking you? They target ads directly to your tastes so our technology contributor Becky Worley has ways to protect your privacy. Consumers are worried about internet privacy. How big tech companies use what we search, read and watch online to create a profile on us. They're trying to infer not only just what your hobbies are but things like your age, race, gender, maybe political views. So they can better target ads at you. Reporter: Is there any way to see specifically what the internet knows about you? Actually, yes. Let's start with the biggest ad company on Earth, Google. You thought they were a search engine, right. Go to my account.google.com and drill in to see how they profiled you. I watch football. Use an apple device and I do live near San Francisco. Why did they track this stuff? More relevant ad the more likely you are to click on it and it turns into the revenue for the big tech companies. Reporter: Twitter, Amazon and a bevy of advertisers built profiles too and let's talk about Facebook. In settings click on ads, it shows what influences the ads will see. They even know what car I own. That just feels creepy. Amazon, Facebook and an alliance of digital sfiezers do let you opt out of tailored ads. Google lets you choose to use their site anonymously and don't profile you if you opt into incognito mode. As for most other sites you can't stop them from collecting data. And there's no way to see what the internet as a whole knows about you except to look at the ads you're being served. Yes, I'm a mother whose children need new 1450us what wants to drive a safe car in my 40s but I don't need pills for my aching joints and I'm not going to wear, is that a frock. No, Facebook, you don't have me pegged yet. For "Good morning America," Becky Worley, ABC news, new York.
This transcript has been automatically generated and may not be 100% accurate.