Causality is arguably one of the most important concepts in science. Establishing causal relationships from data is a difficult problem which involves numerous fields like statistics, computer science, econometrics and machine learning among others. In this talk I share a few practical ideas about solving problems and using techniques related to causality. These are ideas that were very helpful while solving real life problems in Booking.com. Although this is a rather casual talk, beware: There will be Maths.