Sharing location in online social networks

Online social networks (OSNs) have become important media for information sharing among Internet users. In particular, several OSNs provide mechanisms to facilitate sharing of the users' location, which is gaining increased popularity due to the growth of GPS-equipped smartphones. These location-based OSNs (LSNs) bridge users' physical and social worlds, allowing users to know where their friends are and enabling location-based information access and user interactions. In this article we first introduce several LSNs and compare their location-sharing related features. A user's location, however, is sensitive and personal information that may raise significant privacy concerns. To understand real-world users' location-sharing behavior, we collected 21 months of data traces from a commercial LSN and analyzed its users' location-sharing updates. We found that the characteristics of the users' privacy protection behavior is correlated with their age, gender, mobility, and geographic region. In addition, friends tend to have similar privacy protection patterns. To the best of our knowledge, this article is the first large-scale empirical study of a modern LSN.