User data mining is a necessary and desirable commodity to most internet companies. The largest, most fenced-off (behind login), and diversified social media data company on the internet is Facebook. The company collects personal and sensitive data about the user across devices and services in various contexts ranging from activity on Facebook to Check-ins on Foursquare, pictures from Instagram, playlists from Spotify, and running routes in Runkeeper. The users share these data paths of their lives with their network of friends, Facebook, external companies, advertising agencies and app developers. The data becomes ubiquitous, it travels with the user, across devices and services, but how do users navigate in this seamless service? How do they control this interoperability, what is considered sensitive non-sharing data and why? And what are the user strategies of personal data sharing in the seamless and ubiquitous environment of Facebook? This presentation zooms in on this kind of interoperable and seamless communication as one of the main characteristics of the mobile and ubiquitous internet. Drawing on open API data retrieval from Facebook and interviews with high school students Bechmann presents a qualitative study of interoperability and data sharing in the setting of Facebook and exemplifies among others how high school students have a common understanding of personal data and personal data handling, along with a high degree of control by designing their own code of conduct, practices and uses of the Facebook interface and functions in the quest for socializing with their friends.