Physicists are not computer scientists. But at CERN and worldwide, they need to analyze petabytes of data, efficiently. Since more than 20 years now, ROOT helps them with interactive development of analysis algorithms (in the context of the experiments' multi-gigabyte software libraries), serialization of virtually any C++ object, fast statistical and general math tools, and high quality graphics for publications. I.e. ROOT helps physicists transform data into knowledge. The presentation will introduce the life of data, the role of computing for physicists and how physicists analyze data with ROOT. It will sketch out how some of us foresee the development of data analysis given that the rest of the world all of a sudden also has big data tools: where they fit, where they don't, and what's missing.