Cartography 2.0 is a free online knowledge base and e-textbook for students and professionals interested in interactive and animated maps. I (Mark) pitched the idea to my co-authors because I knew that, as teachers, we were all frustrated with the inability of traditional textbooks to keep pace with Web technologies. Nor could we find any comprehensive online resources that provided the same breadth and depth we’ve come to expect from a professionally produced textbook. The kind of knowledge that is needed to make dynamic maps spans many (traditionally separate) fields, and we set out to answer a basic question we’ve been asked many times: What’s the important stuff I need to know about making great on-demand/interactive maps?