Poetry is broken up into segments called feet, with characteristic rhythms or stress patterns. An iamb, for example, is an unstressed syllable followed by a stressed one (think Shakespeare's usual rhythm pattern of iambic pentameter, or lines with five feet each containing an unstressed syllable followed by a stressed one); a dactyl is a stressed syllable followed by two unstressed ones (my high school teacher told us that the Iliad was written in dactylic hexameter, and that was the rhythmic pattern used in the translation we read; Iliad is an example of a dactyl). Similarly, if a section has two unstressed syllables, it is called a pyhrric foot. A spondee has two stressed syllables, and there are a number of other common patterns, each of which is given a name to describe it.
(Editor in Humanities, Literature and Books For Children)
That's all, folks!