"But there is an obvious solution: mandate the operating systems (iOS and Android) to share device users' ages when they download apps from the app stores – data the operating systems get as part of the hardware acquisition already. This would be a simple one-step way for parents to control all the different apps that their kids use (in the US, the average teen uses forty different apps per month) and would remedy the fractured app-by-app approach we have today. We should make a societal judgement about whether to set these age limits for smartphones or social media use at thirteen, fourteen, fifteen or sixteen, then write it into law." in How to Save the Internet by Nick Clegg