Poem Types

Couplets :A unit of verse consisting of two successive lines, usually rhyming and having the same meter and often forming a complete thought or syntactic unit.... a PAIR. 

http://www.answers.com/topic/couplet#ixzz1Dfo12Zoy

Free Verse: unrhymed verse of irregular meter and nonmetrical rhythm

 http://www.answers.com/topic/free-verse#ixzz1DfolTtBg

Haiku:A Japanese lyric verse form having three unrhymed lines of five, seven, and five syllables, traditionally invoking an aspect of nature or the seasons.

 http://www.answers.com/topic/haiku#ixzz1Dfp6kAge

Limerick:A light humorous, nonsensical, or bawdy verse of five anapestic lines usually with the rhyme scheme aabba.

 http://www.answers.com/topic/limerick#ixzz1DfpSZYof

Quatrain:A stanza or poem of four lines.

http://www.answers.com/topic/quatrain