This poetry form called "Hay(na)ku" consists of 3 lines and 6 words, which are arranged like this:
one word in the first line, two in the second, three in the last line.
There are variations possible, so the three-word-line can be the first one and the one-word-line the last one.
Also: multiple Hay(na)kus can be chained so that you create a longer poem.
