If you put photos online you're probably used to social networks wanting to 'tag' you. What I find worrying is that Facebook's DeepFace system is now as accurate as human beings in recognising faces.
Why does this concern me? Maybe I've seen too many movies, but I can imagine ways companies and governments might use this to badger or even oppress citizens.
The software is fascinating. Using 'deep learning' it studies faces in tagged photos to spot them in untagged ones. It can recognise someone regardless of age, pose, illumination and expression.