I have also heard this called Pamphlet Stitch. In some vocabularies it is called 'Sewing a Single Signature' [110339]
The advantage of handstitching in bookbinding is that there is a wide variety of stitches that have been tried and tested. I describe here the simplest stitch, and encourage craftspeople to spend two minutes learning it and then encourage them to consider more adventurous techniques as the need becomes apparent.