What is the definition of a refrain in music and how is it typically used in song composition?

A refrain in music is a repeated section of lyrics and melody that occurs multiple times throughout a song. It serves as a chorus or a hook that is catchy and memorable, helping to unify the song and create a sense of familiarity for the listener. Refrains are often used to emphasize the main theme or message of the song and provide a point of reference for the listener to return to.