Do you have a Roku Or an Amazon Fire TV device? Millions of homes have not just one, but several. We can watch Netflix, Amazon Prime Video, Hulu and free TV shows and movies without a subscription.

A new report shows that while you're watching something on one of these smart streaming devices, someone else is watching you.

The new study by Princeton University found that TVs and streaming gadgets that are connected to the internet have data trackers on them. Researchers discovered the trackers while visiting more than 2,000 channels on the Roku and Amazon Fire TV.

According to the report, 89% of the channels on the Fire TV had trackers. They were also found on 69% of channels offered on the Roku.

The trackers recorded what was being watched, but also the device serial number, city, state, the name of the Wi-Fi network it uses, and an advertising ID. The trackers then shared all of that information over un-encrypted connections, meaning anyone could access it online.

The information is sent to advertising platforms so they can target you with advertising. It's become the biggest revenue source for some TV manufacturers. That's why you're seeing TV prices drop.

Manufacturers make more off the sale of your data than the cost of the TV itself. On top of that, researchers found that turning off "data sharing" in the settings of these devices, did not make much of a difference.

Roku, Amazon Fire TV, and other smart TVs include options in their settings menu to opt-out of or turn off targeted ads. The study found turning those options off doesn’t stop the device from gathering, collecting and sharing the data it receives from your device.