A sestet is a stanza or a poem consisting of six lines. It is commonly used in various poetic forms, including the Petrarchan sonnet, where it follows an octave of eight lines. The sestet often presents a resolution, counterargument, or a shift in tone from the preceding lines. In terms of rhyme schemes, a sestet can vary, but popular patterns include CDCDCD or CDECDE. This structure allows poets to explore themes and ideas in a concise manner, making it a versatile tool in both traditional and contemporary poetry.