Wow, what a fun chapter!
You've made things jump around the page, almost killed your computer and patience with a zoomable map, and made one supremely awesome bar graph. Well done!
In this chapter, we've animated with transitions, interpolators and timers, and then we learned how to do some of that with CSS. We then learned the difference between explanatory and exploratory visualizations, and used interactivity to create the former. We then made some exploratory visualizations by using behaviors with some of our previous projects. Things are starting to look pretty snazzy, aren't they?
In the next chapter, we'll be looking at creating a whole boatload of really pretty charts using D3's black magic — layouts. Combining the skills you've learned ...