"Rock-a-Bye Baby" is a traditional nursery rhyme and lullaby that is often sung to soothe infants. The song describes a baby in a treetop, who is rocked by the wind. The lyrics suggest that if the tree were to fall, the baby would tumble down, creating a sense of vulnerability. The origins of "Rock-a-Bye Baby" date back to the late 17th century, and it has been passed down through generations. It is commonly associated with lullabies and childcare, and is frequently used in children's music and storytelling to help calm babies and young children.