These trackers create a profile of you based on your personal data and online habits. This data includes your location, what sites you visit, and even the way you move and click your mouse around the screen. Social sites, like Facebook, can track almost all your web activity with embedded widgets on various sites and if you're signed into Google, anything you do on your phone and computer are linked together to contribute to this profile too.

For example, the profile will know that you're married, a mom of kids (with another on the way!), that you live in Portland, Maine with a dog, and that you love pizza, horror movies, and yoga. It will also know that you're looking for modern furniture for your home and that you're considering a move to Austin.

This online profile is commoditized and follows you from site to site, showing you targeted ads for things you might buy.