The Shakespearean sonnet affords two additional rhyme endings (a-g, 7 in all) so that each rhyme is heard only once. This enlarges the range of rhyme sounds and words the poet can use and allows the poet to combine the sonnet lines in rhetorically more complex ways.
Sonnet 130 is the only Shakespearean sonnet which models a form of poetry called the blazon, popular in the 16th century used to describe heraldry. It presents a detailed summary of all of the main features and colors of an illustration. A typical blazon of a person would start with the hair and work downward, focusing on eyes, ears, lips, neck, bosom and so on.