From NBC News:
Facial recognition can log you into your iPhone, track criminals through crowds and identify loyal customers in stores.
The technology – which is imperfect but improving rapidly – is based on algorithms that learn how to recognize human faces and the hundreds of ways in which each one is unique.
To do this well, the algorithms must be fed hundreds of thousands of images of a diverse array of faces. Increasingly, those photos are coming from the internet, where they're swept up by the millions without the knowledge of the people who posted them, categorized by age, gender, skin tone and dozens of other metrics, and shared with researchers at universities and companies.
As the algorithms get more advanced – meaning they are better able to identify women and people of color, a task they have historically struggled with – legal experts and civil rights advocates are sounding the alarm on researchers' use of photos of ordinary people. These people's faces are being used without their consent, in order to power technology that could eventually be used to surveil them.