Poetry comes in many forms, some of which have been around for centuries. The sonnet dates back to 13th century Italy. Japanese haiku: evolved from the 16th century; this form and tanka were favorites of the ruling courts. Other poetry styles are newer structures. Free Verse: is the English for vers libre; the term was coined by French Symbolist poets in the late-19th century.
The limerick dates to the mid-19th century. This humorous and often ribald style of poetry was popularized in 1846 by Edward Lear's A Book of Nonsense. A limerick consists of five lines, and thirteen beats (3, 3, 2, 2, 3), and the rhyme scheme is aa, bb, a. The first line most often ends in a place name, and the last line ends with the same word as the first line. Puns and plays on words are usually included. Here's a generic example, often used to show the form:
There once was a man from NantucketAlthough I've written and published poetry, I've never been able to come up with a limerick.
Who kept all his cash in a bucket
But his daughter named Nan
Ran away with a man,
And as for the bucket, Nantucket.
An old woman lived north of HelenaWait a minute. Duh, what rhymes with Helena?