What Are the Rules of Haiku?

The structure of Haiku is as follows:
-there can be only 3 lines
-17 syllabels in total (5 syllables in the first line, 7 syllables in the second and 5 syllables in the third line),
-you don't have to be strict about punctuation and capitalization, it's up to you how to use them,
-haiku poems don't have to rhyme
-usually nature is the subject
-in the first and third line images or ideas should be presented