Elizabeth Barrett Browning's poem "How do I love thee" from her collection "Sonnets from the Portuguese" is an example of a sonnet. This short poem is in the Petrarchan sonnet form.
Sonnets are 14-line rhyming poems in which the first 12 lines lead up to the volta, which is the twist in the last two lines of the poem. These poems are classified into three basic forms, depending on the rhyme scheme, and each is divided into an octave, the first eight lines, and a sestet, the last six lines. Petrarchan sonnets have rhyming ends in the pattern "a b b a a b b a c d c d c d" with some variation in the sestet. Spenserian sonnets, developed in Queen Elizabeth's court, have the pattern "a b a b b c b c c d c d e e," and Shakespearean sonnets are patterned "a b a b c d c d e f e f g g."