Haiku (written) or Senryu (spoken or sang) are 3 line Japanese style short poems or songs with a 5-7-5 syllable pattern. There can be other variations like 3-5-3. Like Japanese minimalist culture, traditionally these poems focus on a single aspect of nature. Modern versions are not as strict.
Example: by Frank G. Poe, Jr.
Brown, dry, autumn leaves
Whispers, floating to the groundMissing tree embrace