What is the definition of a rhyme scheme?

A rhyme scheme is a pattern of rhyming words at the end of lines in a poem or song. The pattern is usually described using letters, with each letter representing a different rhyming sound. For example, the rhyme scheme of the following quatrain is ABAB:

> The cat sat on the mat, (A)

>And looked at the rat. (B)

>The rat ran away, (A)

>In a comical way. (B)

In this example, the words "mat" and "rat" rhyme with each other, and the words "away" and "way" rhyme with each other.

Rhyme schemes can be used to create a variety of effects in poetry and song. They can be used to emphasize certain words or phrases, to create a sense of rhythm or musicality, or to simply add an element of fun or interest to a poem or song.