"A traditional Japanese haiku is a three-line poem with seventeen syllables, written in a 5/7/5 syllable count. Often focusing on images from nature, haiku emphasizes simplicity, intensity, and directness of expression.

Haiku began in thirteenth-century Japan as the opening phrase of renga, an oral poem, generally 100 stanzas long, which was also composed syllabically. The much shorter haiku broke away from renga in the sixteenth-century, and was mastered a century later by Matsuo Basho, who wrote this classic haiku:

     An old pond!
     A frog jumps in—
     the sound of water."

https://www.poets.org/poetsorg/text/haiku-poetic-form