Saddle stitch or saddle staple are ways of describing one of the most popular binding methods
The larger sheets (which are twice the size of the final finished booklet) are collated, folded in half, and have two staples put into the spine to hold it together.
This works very well for books up to 52 pages depending on the thickness of the paper you use for the book. The thicker the paper you use, the fewer sheets can be stapled.
The most economical way to produce these books is as a “self-cover” book where the same paper is used for the cover and the inside pages. However, it can be made to be harder wearing and more substantial by using a heavier artboard cover and even adding a gloss or matte celloglaze or laminate.