* A text-only book: Many books, especially non-fiction, academic, or technical books, do not include illustrations.
* A book with photographs: Instead of illustrations, the book might contain photographs to accompany the text.
* A book with other types of visual elements: Some books might use diagrams, charts, maps, or other visual aids that are not considered traditional illustrations.
It's important to note that the term "illustrator" is often used loosely. Sometimes the author of a book might create the illustrations themselves, or someone else might create the illustrations without being credited.