Haiku (俳句) is one of the most important forms of traditional Japanese poetry. Haiku is a very short poetic form, usually (although by no means necessarily) consisting of three lines of 5, 7, and 5 units each, which are generally applied as syllables when haiku is written in other languages, and usually containing a special word - the kigo - that indicates in which season the haiku is set. Some consider that it must also combine two different images which are related in the third line, be written in present tense and have a pause (the kireji or cutting word) at the end of either the first or second line. All such rules are somewhat arbitrary and are habitually broken by most poets, especially when adapted for languages other than Japanese.
The use of 5, 7, and 5 syllables, as may be taught in grade schools, produces a haiku much longer than any traditionally composed haiku in Japanese, as the Japanese do not count syllables as they are defined in English, but instead count morae (singular mora), units of time, which are generally shorter than the average of English syllables which are highly variable in length. English language poets may produce a more accurate haiku by using the concept of metrical feet rather than syllables. A hiaku then becomes three lines of 2, 3, and 2 metrical feet, with a break or pause after the second or fifth.
The poet must be concise because of the brevity, while concentrating deep spiritual understanding into the poem. The haiku poet usually takes up the changes of nature which have impressed him or her in order to express the intangible world of the spirit. Often, at least in translation, the banal nature of the subject matter of many Japanese haiku is striking.
Haiku is not written only by professionals. Anyone can learn to use the form, although like other forms of poetry it is difficult to master it.
Some famous Japanese masters of the haiku form include Matsuo Basho, Buson, Issa.
An example of classic haiku (by Basho):
More recent well known authors and poets who have written haiku include: Richard Wright.