Thuluth
Thuluth (Persian: ثلث sols, Turkish: Sülüs, from Arabic: ثلث ṯuluṯ "one-third") is a script variety of Islamic calligraphy invented by the Persian Ibn Muqlah Shirazi, which made its first appearance in the 11th century CE (fourth Hijri). The straight angular forms of Kufic were replaced in the new script by curved and oblique lines. In Thuluth, one-third of each letter slopes, from which the name (meaning "a third" in Arabic) comes. It is a large and elegant, cursive script, used in medieval times on mosque decorations. Various calligraphic styles evolved from Thuluth through slight changes of form.
History
The greatest contributions to the evolution of the Thuluth script, occurred during Ottoman Empire in three successive steps that Ottoman Art Historians call "calligraphical revolutions":
The first revolution occurred in the 15th century and was initiated by the Master Calligrapher Şeyh Hamdullah.
The second revolution resulted from the work of the Ottoman calligrapher Hâfız Osman in the 17th century.