POIs (proof-of-individuality) are smart-assets that are hosted on the Ethereum network. They solve one of the hard problems in crypto- how do you prove that a person only has one account within the system ?
Through person-to-person verification. Users are grouped together by random in groups of 5 or so, and every group does a video hangout at the exact same time, that lasts around 10 minutes or so. Users check so that the others in their group aren't doing another hangout at the same time. They then sign each other's POIs and verify them. Once the hangouts are finished and all POIs have been verified, everyone will know that each POI represents a unique human being.