There are various forms of poetry in different languages. “Haiku” is a traditional form of Japanese poetry. Haiku poems consist of 3 lines. The first and last lines of a Haiku have 5 syllables and the middle line has 7 syllables. The lines rarely rhyme.

A haiku is not a poem, it is not literature; it is a hand becoming,
a door half-opened, a mirror wiped clean. It is a way of returning
to nature, to our moon nature, our cherry blossom nature, our
falling leaf nature, in short, to our Buddha nature. It is a way in
which the cold winter rain, the swallows of evening, even the very
day in its hotness, and the length of the night, become truly
alive, share in our humanity, speak their own silent
and expressive language.

– Haiku: Eastern Culture, 1949, Volume One, p. 243.
Translations and commentary by Reginald H. Blyth