Baby and baby are intimate terms for children. It is the nickname of parents or family members for babies or young children. In ancient times, when parents had children, they were all treasures. In the eyes of parents, children are treasures.
Idioms to describe children are ice snow cleverness, naivety, golden couple, cleverness, untidiness, yellow-tongued children, looking dignified and strong, lifelike, precocious and so on.