Once all of the parent sheets have been folded into signatures, the stacks of signatures are taken to the collation machine, which collates the separate signatures into their proper page order. The resulting new stacks of ordered signatures are now called book blocks.

Watch the Collation machine stack signatures in page order to make book blocks.

Collation machines like the one pictured below are large enough to handle books with many hundreds of pages, but books with only two or three signatures can also be collated by hand.

Collation Machine for Sorting Signatures into Book Bodies in Page Order