Open a book flat on a table. If it lies obediently open, it was probably sewn: gatherings of folded sheets stitched through the fold, the oldest structural grammar in the trade. If it fights you, it was probably glued: a “perfect” binding, so called with no irony the trade will admit to.
The sewn book is repairable by design. Threads can be replaced, gatherings re-cased, boards renewed. A sewn text block from the seventeenth century can be rebound in the twenty-first and lose nothing but its old coat. The glued book is a sealed unit; when the adhesive fails, the pages leave one by one, like guests after midnight.
Between these two poles sits every choice a publisher makes about permanence, and the choice is legible if you know the grammar: headbands and a hollow back speak one intention, a cracked hinge of hot-melt speaks another. The maison reads bindings the way a tailor reads a seam.
“When the adhesive fails, the pages leave one by one, like guests after midnight.”
LIBRO editions are sewn. It is slower and it costs more, and it is not a detail. It is the entire argument, made structurally: this book expects to outlive you, and has been built accordingly.