This document discusses how big data from sources like digital transactions, social media, telecommunications, and open data can provide new insights for tourism. It notes that the amount of digital data will grow dramatically from 13 zettabytes in 2005 to over 34 zettabytes by 2020. For tourism, big data can be used to micro-segment tourists and better understand behaviors and flows. Examples show how data on arrivals and visits from countries like China and Germany to cities like Milan can be analyzed at a granular level over time. This detailed data made available through big data has implications for how destinations can generate a competitive advantage and tailor their policies, investments, and promotions.