Side Sewn
A "side sewn" book is one where the thread is passed through the thickness of the book on the edge nearest the spine side - next to the left edge as one faces a closed book oriented for reading.
The advantage of side sewing is the strength it offers. Many text books and catalogs are side sewn. Midwest Editions can side sew and leave an exposed edge as in the example shown, or "case-in" the book with a hard cover, thus hiding the sewing. Side sewn books also offer economy.
One disadvantage to a side sewn binding is that opened books never lie totally flat.
Side Sewn Catalog