While often associated with Shakespeare, the sonnet actually originated in Italy in the 13th century. The word 'sonnet' is derived from the Italian 'sonetto,' meaning 'little song.' Giacomo da Lentini is credited with inventing the form, but it was perfected by the poet Petrarch. A Petrarchan (or Italian) sonnet consists of 14 lines divided into an eight-line 'octave' and a six-line 'sestet.' The transition between these two parts is called the 'volta' or 'turn,' where the poem's argument or mood shifts. When the form reached England in the 16th century, Shakespeare adapted it into what is now known as the English or Shakespearean sonnet. This version consists of three quatrains and a final rhyming couplet, typically written in iambic pentameter. This rigid structure has challenged and inspired poets for nearly 800 years, from John Milton to Elizabeth Barrett Browning.