Before we can discuss how best to visualize data, it is useful to understand a little about your audience: humans. The first thing to understand is that humans have been visualizing things for a long, long time. Some people seem to think that data visualization started some time in 1800, but things were happening a long time before that.
At some unknown stage in human evolution, it suddenly became important to tell stories. In many cultures, the easiest way to tell these stories was to create pictures that would enable the storyteller to show the listeners what was being related:
Bisonte Rupestre en Altamira by Baperukamo—own work
This photograph is licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons and is available at http://commons.wikimedia.org/wiki/File:Bisonte_Rupestre_en_Altamira.jpg#mediaviewer/File:Bisonte_Rupestre_en_Altamira.jpg.
As civilizations grew, the aural transfer of information became...