Facial recognition technology is everywhere, from your iPhone to candy vending machines to the TSA. But it has a problem: It might not recognize you.

In her new book about facial recognition, Kashmir Hill shows how our expectations of privacy have been rewritten over the past few years.

The US Department of Homeland Security (DHS) is piloting facial recognition technologies that can see through face masks with a "promising" level of accuracy, meaning that travelers could end up ...