Before we all started using computers to do our typesetting, there were professional typesetters who knew a lot about type and some rules for setting it appropriately. Much of this information is taught in typography courses at colleges and universities. As I taught students in my own typography class, I felt the need to have some sort of concise resource that would remind them of some of these typesetting conventions. You know, something that would lead them in typographic righteousness and keep them out of sin.