The correct answer to the question “What book is poetry?” is the Book of Psalms or just Psalms. It is the third section of the Hebrew Bible, a book of the Old Testament and is divided into five sections – Book 1 which covers Psalms 1 to 41, Book 2 which covers Psalms 42 to 72, Book 3 which covers Psalms 73 to 89, Book 4 which covers Psalms 90 to 106 and Book 5 which covers Psalms 107 to 150.
Psalms is considered as poetry because all of it are written in poetry rather than prose. One example of this is found in Psalms 119:105 where it was stated: “Your word is a lamp to my feet and a light for my path.”