This document discusses data visualization from a user experience perspective. It begins with an introduction to data visualization, explaining what it is and how visual encodings make data easier to understand. Different types of visualizations are described for showing relationships in data, such as time series, hierarchies, maps, distributions, and comparisons. Design decisions around data and perception are also covered. The document concludes with considerations for the user experience of data visualizations, such as interactivity, navigation, and dividing complex data into multiple coordinated views.