Does a haiku have to be about nature?

Related questions

1. What to write limericks about?
2. How do you write a limerick poem?
3. Is a Limerick a type of Irish poem?
4. What are the characteristics of a limerick?
5. What is Limerick literature?
6. What county is Limerick?
7. How many beats does a limerick have?
8. Is Limerick safe to visit?
9. What is a haiku poem?
10. What is a 5 line poem called?

Tags

1. #often
2. #forms
3. #there
4. #overall
5. #others
6. #simply
7. #number
8. #shorter
9. #written
10. #subject
11. #count
12. #small
13. #variations
14. #nature
15. #occasionally
16. #limited
17. #haiku
18. #syllables
19. #poems
20. #longer
21. #lines