___Waka originally encompassed a variety of forms, such as choka, tanka and sedoka, but tanka gradually became the predominant form until, from the Heian Era (late 8th century), the term waka came to be considered synonymous with tanka.

___As a short form of lyric poetry, tanka stresses the beauty of life and nature, and a feeling of yearning is an important element. What is sought within this simple form of is to express the essence of this yearning with a depth in which all the emotions are intermingled. The vivid expression of that which has touched the heart has power to evoke a wealth of associations. This allusive feeling contained in these 31 syllables is referred to as yojo. In content, a tanka poem should include this yojo.

___Basho MATSUO, in the middle of the Edo period (late 17th century), gave independent life to the hokku (opening verse) of the haikairenga (linked verse), and established it as an art form dealing with life and nature, using aesthetic values such as the austere elegance called sabi, shiori, in which there is a natural expression of delicate beauty, and karumi, which seeks a refined interest in plain everyday material.

___A feature of haiku is inclusion of a "season word", referring to an animal, plant, event or custom of the season. For example, the season word sumireso (violets) will bring to mind the warmth of spring and violets in bloom along a mountain path. Thus, breadth and depth is given to haiku, the shortest of poems.

___Haiku gives an objective, fleeting picture of its subject. As it is impossible to depict an actual scene in detail, it is necessary to abbreviate to the essentials, and the season word is one such abbreviation.