Defining the word poem isn’t that simple. Basically, it’s any collection of written or spoken words that have some sort of lyrical quality, rhythm, and/or structure that’s less straightforward than a series of sentences is.
There aren’t really any rules for poetry in general: You can play with punctuation, rhyme schemes, formatting, grammar, and everything else as you like. But there are rules for specific types of poems. A haiku, for example, is traditionally a three-line poem whose first and third lines comprise five syllables, and whose second line has seven.
A sonnet is just another type of poem, in the same way that an apple is a type of fruit. And much like there are different varieties of apples—honeycrisp, Granny Smith, etc.—there are different sonnet varieties, each with its own defining features.
All of them, however, must have 14 lines and a rhyme scheme. How those lines are broken up (and which ones rhyme) depends on the type of sonnet.
Types of Sonnets
Petrarchan sonnets—named for Petrarch, the 14th-century Italian poet who gained fame for writing them—contain an eight-line stanza called an “octave,” followed by a six-line stanza called a “sestet.” The octave’s rhyme scheme is ABBAABBA, while the sestet’s is either CDECDE or CDCCDC. Elizabeth Barrett Browning’s “How Do I Love Thee?” (which starts out with “How do I love thee? Let me count the ways”) is a good example of a Petrarchan sonnet.
The other main sonnet variety is the Shakespearean sonnet, whose namesake hardly needs an introduction. Shakespeare split his sonnets into three four-line stanzas (quatrains) and a closing two-line stanza (couplet). He switched up the rhyme scheme, too: ABAB CDCD EFEF GG. Sonnet 130, which begins with “My mistress’ eyes are nothing like the sun,” is one of the Bard’s most iconic contributions to the form.
As illustrated by that poem and Browning’s “How Do I Love Thee?”, sonnets are usually love poems written in iambic pentameter. But plenty of poets have deviated from those norms and broken the other structural rules laid out by Petrarch and Shakespeare. The whole reason we have Shakespearean sonnets in the first place is because Shakespeare decided to break Petrarch’s rules.
John Milton, for example, kept Petrarch’s rhyme scheme, but didn’t separate his 14 lines into two stanzas; he was also known for bypassing love in favor of political and existential themes. Milton’s work was so influential that we now call similar sonnets “Miltonic sonnets.” Edmund Spenser’s sonnets were noteworthy enough to merit their own subcategory, too. Spenserian sonnets follow Shakespeare’s structure of stanzas, but have a more cohesive rhyme scheme: ABAB BCBC CDCD EE.
In summation, a sonnet is a 14-line poem with a fixed set of rules involving stanza breaks and rhyme schemes. But since poetry is all about experimentation and self-expression, feel free to take a page out of Shakespeare’s book and just make up your own guidelines.
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