This is the 9th volume of the picture book series "책좋아 (Chek Joa, I Like Books)" by Woongjin, widely read among Korean children. The title is "동물들의 나이 자랑 (Animals Bragging About Their Age)". It is a hardcover book, designed to be resistant to dirt and tearing, even when handled by children. It is suitable for children aged 4 to around 1st grade of elementary school and is ideal for reading aloud. The author (글: text) is 양연주 (Yang Yeon-ju), and the illustrator (그림: picture) is 유정연 (Yoo Jeong-yeon).