Hi Nick!
Excellent question! And I'm so so sorry that the kanban community have messed this up for you (and me). There's people that claim that they understand sentences like this:
"the purpose of kanban is to eliminate the kanban". To which I just say pheee-ew.
Here's my understanding of it (you can be sure that there will be people going against this too):
• The “Kanban” method (capital K)—refers to a method to create evolutionary change in your organization, formulated by David J. Anderson.
• “kanban” (lowercase k)—refers to the process management system that signals to its users that a need for more work exists. Applied to system development, it’s pretty much everything that we describe in this book
• “kanban system”—this is the system that is set up to track the work in process. An example of this might be a kanban board, the
cards, and the policies around your work. All of that is your kanban system.
Hopefully this clarifies things for you. In short—this book talks about “kanban” and “kanban systems” for software development.