The introduction of smartphones equipped with a front camera and constantly connected to social networks has encouraged the spread of user­generated content of multimedia nature. This led to the emergence of new social phenomena that have a strong impact on society., like the selfie, a modern evolution of the self­portrait usually taken with a digital camera or a camera phone. In the last three years, especially on Instagram, the selfie trend got popularity. Defined in 2013 as "a photograph that one has taken of oneself, typically one taken with a smartphone or webcam and shared via social media", by the Oxford Dictionary, which added selfie to its lexicon and then named it name of the year. This work analyzes the phenomenon inside Instagram, a mobile social­based network created specifically for image sharing. Given the strong social implications, we tried to understand the origin of this practice, the psychological and sociological reasons that gave birth to the trend. Then, through the web­based platform ALOS (A Lot Of Selfies) we collected information from instagram, performed face recognition and calculated statistics about the trend. As a case study, over 2 million selfies shared on Instagram in January­February 2015 were analyzed. This highlighted how the selfie phenomenon is perceived differently in various cultures and societies. In particular, the results show that factors such religion, sex, customs and geo­political situations affect the space­time distribution of selfies around the world.