Haiku is an old japanese form of poetry of one fix verse containing 17 (5-7-5) letters.
In reality, they are sometimes shorter, since for example even a 'coma' is counted as a letter. Traditionally, it should also consist of a season-related expression (季語 kigo).
静けさに
ゆく又來る
冬の月
Into silence
goes and comes back
the winter moon.
春の朝
落葉で眠る
雨滴の子
One spring morning,
on a fallen leaf sleeps,
a drop of dew.