1) The document discusses data visualization and communication of big data. It focuses on analyzing and visualizing real-time sensor data from networks of tiny sensor nodes.
2) Processing, analyzing, and communicating big data from internet activity and expanding sensor networks presents challenges for data visualization. Data scientists help address these challenges.
3) The document discusses classifying sensor data dimensions and properties in order to select appropriate visualizations, and provides Python as a programming language for working with sensor network data and creating visualizations.