Board books are books with pages that are each made of thick paperboard rather than thin paper stock. This binding is perfect for children’s books, since the paperboard makes the book durable enough to survive a lot of hands-on attention from small children, while the thick paperboard also makes it easy for little fingers to turn pages without assistance. Most board books also use rounded corners to prevent paper cuts.
The board book binding methodology is not actually technically “binding” at all. Each set of 2 pages is printed, cut, and then glued by hand to blank paperboard. From there, each set of 2 pages is glued together one at a time. Finally, The cover paper is wrapped and glued around the body. Board books traditionally use a laminated finished on all pages, to increase durability and protect them from the intense handling they usually receive when in use.
Because these books are assembled by hand 2 pages at a time, they do not follow the standard page count multiple of 4 rule. Instead your final page count can be an increment of 2.