A sonnet is a fourteen-line poem following certain conventions of rhyme and meter. It originated in Italy in the fourteenth century, where it was used by such literary giants as Dante Alighieri and Guido Cavalcanti, but was made famous by Francesco Petrarch, who established the conventions of the Italian sonnet—often called the Petrarchan sonnet—in form and content, rhapsodizing about the vicissitudes of romantic love. The Petrarchan sonnet is divided into two parts, the octave (the first eight lines), and the sestet (the final six lines). A change in tone occurs after the octave, often with the first part of the sonnet setting up a problem that the second part resolves.
The first sonnets written in English appeared in the sixteenth century and were heavily influenced by Petrarch. Indeed, among the earliest sonnets in English, written by Sir Thomas Wyatt and Henry Howard, Earl of Surrey, were translations of Petrarch. Sonnets continued to be written in England throughout the sixteenth century, notably by Sir Philip Sidney and Edmund Spenser, and, in the early seventeenth century, Shakespeare’s sonnets, the most influential in English, were published. The type of sonnet made famous by Shakespeare—now known as the Shakespearian sonnet—differs somewhat from the Petrarchan sonnet. The Shakespearian sonnet consists of three quatrains (stanzas of four lines each) followed by a couplet (two rhymed lines), and is usually written in iambic pentameter. The change of tone after the first eight lines is not as strictly adhered to as it is in the Italian sonnet, but is still sometimes employed. And with Shakespeare, the content of the sonnet is no longer restricted to the bitter delights of loving a beautiful woman, but is expanded to include even such topics as are directly contrary to Petrarchan conventions, i.e., a realistic appraisal of the beloved, with her flaws in full view.
Poets writing in English have continued to write sonnets, both in the Italian and the Shakespearian forms, ever since Wyatt and Surrey first made it known to Britons, and, seven centuries after its inception, the sonnet appears to be in no danger of falling into disuse.