What is the exposition of bud not buddy?

Exposition: is the introductory background information on characters and situation, usually given before the action of the story begins.

Bud is a 10 year old boy who has had a tough life growing up he has lived in a "home" (foster home) since his mother died. Bud is also determined to find his father who he thinks is Hermen E. Calloway because his and his moms last name sound the same.