An essay the you write to persuade someone to do something. Mostly used by sales representatives.
Answer: an area of open land, especially one planted with crops or pasture, typically bounded by hedges or fences.
In poetry, 'free verse' is an open form of poetry, so there are no rhyming schemes, you can write whichever rhyme you want, and the meter (the accents and the number of syllables) is also random.
A 'haiku' is a short Japanese poem, consisting of 3 lines, where the first and last lines have 5 syllables, and the middle line 7.