A quatrain is a type of stanza, or a complete poem, consisting of four lines.

Existing in a variety of forms, the quatrain appears in poems from the poetic traditions of various ancient civilizations including Persia, Ancient India, Ancient Greece, Ancient Rome, and China, and continues into the 21st century, where it is seen in works published in many languages.

This form of poetry has been continually popular in Iran since the medieval period, as Ruba'is form; an important faction of the vast repertoire of Persian poetry, with famous poets such as Omar Khayyam and Mahsati Ganjavi of Seljuk Persia writing poetry only in this format.

Michel de Nostredame (Nostradamus) used the quatrain form to deliver his famous prophecies in the 16th century.

There are fifteen possible rhyme schemes, but the most traditional and common are ABAA, AAAA, ABAB, and ABBA.