Like Emacs, this book is cost-free.

It is free because there people who are reading it on borrowed laptops, who use a free editor because they have to, and face enough challenges without needing to choose between learning a skill and their next meal.

And even though it is free of cost, I am asking you to spend your most valuable resource of all: your time.

If you feel that time was well spent, if you can afford your computer, and have the security of a stable job and the safety of a roof over your head, please support this book.