A stanza is a group of lines in a poem. A stanza could have 3 lines in it, 2 lines in it, 4 lines in it, but poets rarely use more than 4. Here are some examples:
6 stanzas, 3 or 4 lines each:
http://www.poets.org/viewmedia.php/prmMID/15377
3 stanzas, 4 lines each:
http://www.poetryfoundation.org/poem/171619
6 stanzas, various number of lines in each:
http://www.poemhunter.com/poem/annabel-lee/
what is stanza
1 answer