A quatrain is a stanza of four lines. It is one of the most common and versatile units in English poetry.

Quatrains appear in ballads, hymns, sonnets (as the building blocks of the Shakespearean form), and countless lyrics. Rhyme schemes vary—abab, abba, aabb, and others—each producing a different sense of closure or forward motion. The four-line span is long enough to develop a thought or image and short enough to remain memorable and singable.

Because the quatrain is so familiar, poets can either lean into its expectations or work against them. A sequence of quatrains can create a steady, cumulative rhythm; a single quatrain can stand as a complete epigrammatic poem. The form’s simplicity is also its strength: it invites clarity and balance.

Four lines grouped as a formal unit constitute a quatrain.