A sonnet is a poetic form originating in Italy consisting of 14 lines that follow a strict rhyme scheme and structure. The two main types are the Petrarchan sonnet and the Shakespearean sonnet. The Petrarchan sonnet has an octave rhyming ABBA ABBA followed by a sestet with a rhyme scheme of CDE CDE. The Shakespearean sonnet has a rhyme scheme of ABBA CDDC EFEF GG with a volta after the third quatrain. Famous sonnet writers include Shakespeare, who wrote 154, and Milton's sonnet "On His Blindness" follows the Petrarchan structure.