This document discusses the history and importance of data visualization (Data Viz). It provides examples of early pioneers of data viz from the 18th and 19th centuries, including William Playfair, John Snow, and Andre-Michel Guerry. These individuals made important contributions to modern data visualization through their early charts, graphs, and maps. The document also discusses the open-source E2D3 data viz platform and how it can be used to create interactive data visualizations from Excel files or other data sources.