Data science is about using data to provide insight and evidence that can lead business, government and academic leaders to make better decisions. However, making sense of the large data sets now becoming ubiquitous is difficult, and it is crucial to use appropriate tools that will drive smart decisions.The beginning and end of nearly any problem in data science is a visualization—first, for understanding the shape and structure of the raw data and, second, for communicating the final results to drive decision making. In either case, the goal is to expose the essential properties of the data in a way that can be perceived and understood by the human visual system.