Tughras (Ottoman Turkish: طغراء; Ṭuğrā) is a signature or a seal of an Ottoman Sultan used in his official documentations as well as minted on coins of his reign. Every sultan in the Ottoman empire had his own Tughra and it is drawn by the court calligrapher or nişancı. It is also used by leaders of other countries such as the former president of Russia Vladimir Putin and the Japanese Emperor Akihito. It is also used by former Turkic states such as the Khanate of Kazan.
Scanned from an image of an original document (Mulkname) in the Istanbul Topkapi Palace Museum Archives. Document from reign of Orhan I (1326-1359). This is officially the first Tughra for an Ottoman Sultan
Tughra of Süleyman the Magnificent (1520). Tughras are often heavily decorated since it is the signature of the reigning Sultan. It is also designed to be complex as to deter counterfeits of the signature.
Detail of the Ottoman Tughra, at the Gate of Felicity in the Topkapi Palace in Istanbul.