John Milton’s Italian-patterned sonnets (later known as “Miltonic” sonnets) added several important refinements to the form. In Sonnet 130 of William Shakespeare’s epic sonnet cycle, the first twelve lines compare the speaker’s mistress unfavorably with nature’s beauties, but the concluding couplet swerves in a surprising direction. The couplet plays a pivotal role, usually arriving in the form of a conclusion, amplification, or even refutation of the previous three stanzas, often creating an epiphanic quality to the end.

Here, three quatrains and a couplet follow this rhyme scheme: abab, cdcd, efef, gg.

The second major type of sonnet, the Shakespearean, or English sonnet, follows a different set of rules. This structure has been noted to lend itself much better to the comparatively rhyme-poor English language. Henry Howard, Earl of Surrey, a contemporary of Wyatt’s, whose own translations of Petrarch are considered more faithful to the original though less fine to the ear, modified the Petrarchan, thus establishing the structure that became known as the Shakespearean sonnet. His famed translations of Petrarch’s sonnets, as well as his own sonnets, drew fast attention to the form. Sir Thomas Wyatt introduced the Petrarchan sonnet to England in the early sixteenth century.

This turn marks a shift in the direction of the foregoing argument or narrative, turning the sestet into the vehicle for the counterargument, clarification, or whatever answer the octave demands. Since the Petrarchan presents an argument, observation, question, or some other answerable charge in the octave, a turn, or volta, occurs between the eighth and ninth lines. The tightly woven rhyme scheme, abba, abba, cdecde, or cdcdcd, is suited for the rhyme-rich Italian language, though there are many fine examples in English. Named after one of its greatest practitioners, the Italian poet Petrarch, the Petrarchan sonnet is divided into two stanzas, the octave (the first eight lines) followed by the answering sestet (the final six lines). The first and most common sonnet is the Petrarchan, or Italian. Two sonnet forms provide the models from which all other sonnets are formed: the Petrarchan and the Shakespearean. The name is taken from the Italian sonetto, which means “a little sound or song.”

Traditionally, the sonnet is a fourteen-line poem written in iambic pentameter, employing one of several rhyme schemes, and adhering to a tightly structured thematic organization. The sonnet is a popular classical form that has compelled poets for centuries.

Sonnet 18 iambic pentameter analysis