Hokku is the first verse of the traditional Japanese poetry form of tanka. During the 9th through 12th centuries, tanka was a widely practiced form of poetry and dealt with courtly and religious subjects. Consisting of a five line structure with 5-7-5-7-7 morae, or syllables, many tanka passages were often combined to form a long poem called a renga. It became common for each of these passages to be written by different authors, however the hokku, or beginning passage, was regarded with special importance. Hence, the composer of the hokku was revered by his fellow poets.
The hokku initiated the tanka and entire renga by establishing the setting for the poem. The hokku accomplished this by using Kigo, words that referred to specific seasonal markers, or Kidai, activities and events that were specific to a certain season. In the 1890’s, the works of Masaoka Shiki broke off the hokku from the tanka and enabled it to stand as its own poetic form. This independence marks the birth of the haiku. Hence, scholars refer to a writer as a haiku poet only if the work was written after Shiki’s 1892 reform.