Most of Shakespeare's Sonnets are arranged in <u>three quatrains</u> (a stanza with four lines) and <u>one couplet</u> (a stanza with two lines), having a rhyme scheme ABAB CDCD EFEF GG.
This means that, for the three quatrains, the first line of each stanza will rhyme with the third, and the second line with the fourth. However, there is no rhyme that exceeds the end of a stanza. The couplet can only rhyme with itself.
