Smart TVs quietly record what people watch and sell that data to advertisers, which is bad for consumers and their privacy.

• Once a TV connects to the internet and the user agrees to the license terms, nearly everything on the screen can be sent back to the maker and its ad partners.
• The tracking works by taking snapshots of the screen many times a second and matching them against a database of known shows and movies.
• It captures Netflix, YouTube, and even game consoles or other devices plugged into the TV.
• From that, companies build ad profiles that can guess a person's age, income, location, race, politics, and religion.
• TV ratings used to require paid, opt-in volunteers; now the tracking is automatic and buried in the fine print.

Outlook: Privacy advocates and tech reviewers are pushing for new laws to limit or ban this kind of TV tracking.