A poem of fourteen lines is a sonnet. Sonnets typically follow a specific rhyme scheme and are often divided into two parts: an octave (eight lines) and a sestet (six lines). The most famous type of sonnet is the Shakespearean sonnet, which has the rhyme scheme ABAB CDCD EFEF GG in its 14 lines. Sonnets are often used to explore themes of love, beauty, and mortality.