This diagram (above) gives a pictorial overview of the kinds of C++ classes in Audacity. You can hover over each tile to see more about the groups of classes.
Snakes of Classes
The snake diagram (above) groups the C++ classes into several 'snakes'. The size of the circles is an indicator of how much code comments there are about each class. Red snakes are very specific to Audacity. Blue snakes are more abstract and more likely to be reusable in some form in other projects.
The snake diagram is a bit too crowded - there are over 600 classes described. The intention is that as more write up is done, each of the tiles will lead to a small number of snakes and more write up.