The paradelle is a very rigid, modern poetic form. According to Wikipedia:

Billy Collins originally said the paradelle was invented in 11th-century France, but he later admitted that he invented it himself to parody strict forms of poetry, particularly the villanelle. His sample paradelle, "Paradelle for Susan" (c. 1997), was seemingly intentionally terrible, completing the final stanza with the line "Darken the mountain, time and find was my into it was with to to".

Despite it's satirical beginnings, people have gone on to write some very beautiful paradelles. The tricky part is that you must re-use words introduced in previous couplets and stanzas in later couplets and stanzas. This editor exists to help you keep track of the words you need to use.

• The paradelle is a 4-stanza poem.
• Each stanza consists of 6 lines.
• For the first 3 stanzas: the 1st and 2nd lines should be the same; the 3rd and 4th lines should also be the same; and the 5th and 6th lines should be composed of all the words from the 1st and 3rd lines and only the words from the 1st and 3rd lines.
• The final stanza should be composed of all the words in the 5th and 6th lines of the first three stanzas and only the words from the 5th and 6th lines of the first three stanzas.