A haiku is a Japanese poem with three lines. The first and last line have 5 moras and the middle line having 7 moras that focus on nature. It started out as a popular activity in Japan in the 9th to 12th centuries called "tanka". The word "haiku" came from the word "hokku" which is the first verse for tanka because hokku sets the mood for the rest of the verse. The verse itself had three lines and 17 syllables in total. Later on, hokku was read as an individual poem and thus became haiku in the 19th century.

Sample of Haiku:                    

An old silent pond...

A frog jumps into the pond,

splash! Silence again.