The document discusses conventions of Shakespearean sonnets. It begins by explaining the typical structure of a Shakespearean sonnet as consisting of three quatrains followed by a couplet, all written in iambic pentameter. It then provides an example sonnet by Shakespeare, analyzing elements of its structure, metaphor, and rhyme scheme. The summary discusses how the first eight lines set up an extended metaphor about nature and seasons, while the final sestet presents a "turn" where the speaker claims his subject's beauty will be eternal unlike nature.