1) Rhyme is the repetition of similar or identical sounds, typically at the ends of lines in verse. There can be full rhymes with identical vowel and consonant sounds, or incomplete rhymes with variations.
2) Modifications to rhyming include compound or broken rhymes where one or more words rhyme with a combination of words, and eye rhymes where the letters but not sounds are identical.
3) Rhymes can be arranged in different patterns within a stanza, such as couplets where successive lines rhyme, or abab cross rhymes. Internal rhymes place rhyming words within rather than at the ends of lines.