It requires nineteen-lines with two repeating rhymes and two refrains. Five tercets followed by a quatrain make up the form. It is highly structured and has a strict rhyme scheme.
The villanelle is a nineteen line poem adhering to a strict rhyme scheme: A1 b A2 / a b A1 / a b A2 / a b A1 / a b A2 / a b A1 A2, in which the A1 and A2 words remain constant throughout.
