Facial recognition technology is increasingly being used today in many places in the United States and overseas. Such systems use machine learning tools to scan faces in an attempt to recognize particular individuals. Many police agencies across the world have long used facial recognition technology to search for and help catch criminals. The technology has also been used at some U.S. airports to help confirm the identity of passengers and get them on flights. It is also used to unlock phones or other electronic devices, and in some cases, even cars. Some robots use facial recognition to recognize the people it is communicating with. Now, a similar technology, known as facial detection, is entering a new field: the business of advertising.