Chapter 1: Introduction
Since this is an introductory chapter, and the reader is not supposed to understand the aims and scope of data visualization, let alone its technicalities, we do not provide sample code here.
However, this page lists a number of internet resources that can be browsed (and, in the case of tools, interactively tried out). This allows getting a better idea about what data visualization is, can do, and also what are its challenges.
50 examples of data visualization
This site lists an interesting set of visualization examples, with a focus on information visualization. Many examples are tools that you can try online, with no technical knowledge!
Examples of visualization (external site)