some variations/permutations of the couplet:
- the heroic couplet, which is always in iambic pentameter, gets its name from the form used in various 17th and 18th century translations of heroic epics
- closed couplets end definitively, usually with a period or some such signifier, while open couplets can flow with the same idea from one to the next
- triplets add a third rhyming line as a variation (as opposed to the tercet, which is three lines to begin with)
- the alexandrine is another variation, generally used as a last line (and often as the third of a triplet); it has twelve syllables, and emphasizes the end of the poem, and usually offers some sort of summary or punch line as well