Casing-in
Also called casing
The operation that joins the book block, already sewn or glued, to the hardback case made separately: the block is fixed into its case by the endpapers pasted to the boards.
In practice
It is the step that gives the book its hard cover, and it shows: careful casing-in leaves even squares and a book that closes straight. It adds time to the schedule, so plan for it from the quote. Do not confuse it with a slipcase, which is a box the finished book slides into.