The tughra was the calligraphic emblem and official seal of an Ottoman sultan.
Each Ottoman sultan had an individual tughra, designed near the beginning of his reign by a court calligrapher or the nişancı, a senior official responsible for chancery work. It appeared on imperial decrees, grants, correspondence, coins, and seals, marking the authority of both the ruler and the state.
The emblem’s distinctive form combines the sultan’s name and lineage with highly stylized strokes. It commonly includes three tall vertical lines, two looping forms on the left, and sweeping extensions on the right. Although difficult to read at a glance, the design was meant to be recognizable and hard to forge.
Mühr simply means a seal, while hilye is a calligraphic description of the Prophet Muhammad’s qualities. Tazhib refers to the decorative gilding and illumination used in manuscripts. These may accompany Ottoman calligraphy, but none is the sultan’s specific official emblem.