What structure is commonly used by Shakespeare in his poetry?

Shakespeare is renowned for his use of the sonnet form in his poetry, particularly the Shakespearean sonnet, which is characterized by its specific structure of 14 lines divided into three quatrains followed by a rhymed couplet. This structure allows for a development of thought, argument, or theme throughout the quatrains, culminating in a final, reflective couplet that often provides a twist or resolution. The specific rhyme scheme (ABABCDCDEFEFGG) and iambic pentameter are hallmarks of Shakespeare's sonnets, contributing to their rhythmic beauty and emotional depth.

While free verse is a style that avoids traditional meter and rhyme, and stanza refers more broadly to any grouping of lines in poetry without specifying a particular structure, and couplet signifies just a two-line unit, it is the sonnet that is most intricately tied to Shakespeare's legacy. His mastery of the sonnet form has had a enduring influence on English literature, making it the correct choice in identifying the structure he is commonly associated with.