Facial recognition is increasingly common, but how does it work?

This article was originally published on The Conversation. The Trump administration's efforts to impose new immigration rules drew attention -- and legal fire -- for its restrictions on the ability of people born in certain majority Muslim countries to enter the U.S. In the frenzy of concern, an obscure piece of the executive orders did not get scrutinized, or even noticed, very much: its expansion of facial recognition systems in major U.S. airports to monitor people leaving the U.S., in hopes of catching people who have overstayed their visas or are wanted in criminal investigations. It's a much more powerful version of the method your phone or computer might use to identify friends in your photos. Using computers to recognize people's faces and validate their identities can streamline access control for secure corporate and government buildings or devices. Some systems can identify known or suspected criminals.