  Facebook, the most popular Online social network is a virtual environment
where users share information and are in contact with friends. Apart from many
useful aspects, there is a large amount of personal and sensitive information
publicly available that is accessible to external entities/users. In this paper
we study the public exposure of Facebook profile attributes to understand what
type of attributes are considered more sensitive by Facebook users in terms of
privacy, and thus are rarely disclosed, and which attributes are available in
most Facebook profiles. Furthermore, we also analyze the public exposure of
Facebook users by accounting the number of attributes that users make publicly
available on average. To complete our analysis we have crawled the profile
information of 479K randomly selected Facebook users. Finally, in order to
demonstrate the utility of the publicly available information in Facebook
profiles we show in this paper three case studies. The first one carries out a
gender-based analysis to understand whether men or women share more or less
information. The second case study depicts the age distribution of Facebook
users. The last case study uses data inferred from Facebook profiles to map the
distribution of worldwide population across cities according to its size.
