The sonnet is a lyrical form of poetry that has 14 lines organized into an octave and a sestet. This form of poetry was introduced in England by Wyatt that translated a Petrarch's sonnet in English. Sonnets that follows Petrarch's model are organized into 2 quatrains and 2 triplets, but later in England Henry Howard Earl of Surrey introduced a new model that was organized in 3 quatrains, that pose the problem in three different ways, and 1 couplet, that tries to provide an answer, and sonnets that followed this model were later called Elizabethan or Shakespearian's sonnets.

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,

This is a sonnet of Shakespeare that follows Elizabethan sonnet model. He wrote this sonnet referring to one of the most important figures of his texts: the fair youth, an unknown young that is indicated only with the initials W. H.. Shakespeare tries to compare this figure to the summer, and this means that he is a beautiful young, but the author understands that it is really difficult to do because he is so good-looking that he is incomparable to the summer because he is eternal and the Summer lasts only three months. All in this sonnet is prone to the eternal.