Shall I compare thee to a summer's day?
Thou art more lovely and more temperate:
Rough winds do shake the darling buds of May,
And summer's lease hath all too short a date:
Sometime too hot the eye of heaven shines,
And often is his gold complexion dimmed,
And every fair from fair sometime declines,
By chance, or nature's changing course untrimmed:
But thy eternal summer shall not fade,
Nor lose possession of that fair thou ow'st,
Nor shall death brag thou wander'st in his shade,
When in eternal lines to time thou grow'st,
So long as men can breathe, or eyes can see,
So long lives this, and this gives life to thee.
This is sonnet 18 by William Shakespeare. It is the most often cited, partially because of its beauty, but also because it is an excellent example of the form of a sonnet.
Sonnets are poems of fourteen lines, which usually follow the rhyming pattern abab cdcd efef gg. This means that in the first four lines, the first and third lines have end-rhymes, and the second and fourth do. The same pattern applies in the next two quatrains, which means a group of four lines. The last two lines rhyme with each other, and they are called a couplet.
There is more than one type of sonnet, but they are usually lyric poems (meaning poems about personal feelings rather than, say, heroic deeds or historical events) of a "single stanza of fourteen iambic pentameter lines linked by an intricate rhyme scheme" (Abrams 299). Early English sonnets (by poets like Sir Thomas Wyatt) were Petrarchan (or Italian) sonnets, and they followed this pattern; eight lines (an octave) rhyming abbaabba, then followed by a sested (six lines) which rhyme cdecde. Other poets in later times (such as Milton) used this form in later centuries.
Early in the sixteenth century the poet Henry Howard, Earl of Surrey, and others, developed a form of the sonnet called the English or Shakespearean sonnet (so called later on because of Shakespeare's prowess at the form). The poem above is this form.
The meter, iambic pentameter, consists of five iambic poetic feet (that is one unstressed syllable followed by one stressed syllable) is one that is also a defining characteristic of sonnets. Note in the poem above how the meter, or the rhythm, of the lines goes like this:
Shall I compare thee to a summer's day
Not every single line in a sonnet must be rigidly iambic, but if there are extra unstressed syllables they are usually elided -- that is, run over, slightly -- while reading. The number of feet, five, is generally adhered to, but depending on the reader's accent and style one more or one less foot in a line may appear. Slight variations in meter make the sonnet more interesting, rather than detracting from its beauty. The sonnet is a flexible style; short enough to limit the poet to a single complete thought, but long enough to give room for wordplay and development of ideas and imagery. It has been used by many English-language poets for almost five hundred years.
Source: Abrams, M. H. A Glossary of Literary Terms. Boston: Thomson Wadsworth, 2005.