These letters indicate exactly where the rhymes take place at the end of the lines. In ABAB, the initial and third lines rhyme at the end, as do the 2nd and fourth strains. In ABCB, just the 2nd and fourth strains rhyme at the tip. Moreover, the rhymes “Sea” and https://types-of-rhymes-in-poetry18410.jiliblog.com/84773150/the-ultimate-guide-to-types-of-rhymes-in-poems