Rook endgames are the most frequently recurring endgames and also one of the most exciting areas of chess, with mind bending tactical opportunities and dizzying nuances available. They have unsurprisingly been a big topic in endgame literature, with a heavy focus on the set theoretical positions and their logic and fixed conclusions (see the excellent Theoretical Rook Endgames by GM Sam Shankland, published as a sister volume to this book as the peak example of this).
Conceptual Rook Endgames goes in a different direction. Focused on two dozen major concepts, the book explains the mechanisms of rook endgames in a novel way, by building foundations with simple examples, which can be seen in the most complicated examples as well. Rook endgames will remain rich and surprising, as they are for the greats, but armed with this book, your comprehension of them will skyrocket.