It's a free book in which folks who participate in Hackerspaces write about their organizations and their spaces. Hackerspaces are tangled up with the Maker movement: folks who chip in to form a space in which they can make stuff. They need to get organized. They need equipment. They need projects and people enthusiastic to work on those projects. They learn from each other, they collaborate, they make things better than they could have on their own. It doesn't always go well; organizations fall apart, spaces are ruined. But it goes well some of the time, and that's a good thing. You might learn something by reading essays from folks who have tried to make it work.