In addition to his formidable output as a playwright, William Shakespeare wrote a particular form of poem called a sonnet. He is credited with 154 sonnets, almost all of which follow the same format. Each consists of four stanzas, arranged in a rhyming scheme known as ABAB--the last words of the first and second lines rhyme with the last words of the third and fourth lines, respectively. After these twelve lines, Shakespeare finishes with a rhyming couplet. By way of example, here is perhaps his most famous sonnet, number eighteen of the 154. Note the rhyme scheme described above:

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.

Shakespeare's style was different than the conventional sonnet developed by the Italian poet Petrarch. Some other English sonneteers were also experimenting with the style at the time, however, but the fourteen-line format with three stanzas and a rhyming couplet has become known as a "Shakespearean sonnet."