The Ottoman Dynasty (or the Imperial House of Osman) (Turkish: Osmanlı Hânedanı) ruled the Ottoman Empire from 1299 to 1922, beginning with Osman I (not counting his father, Ertuğrul), though the dynasty was not proclaimed until Orhan Bey declared himself sultan. Before that the tribe/dynasty might have been known as Söğüt but was renamed Osmanlı (Ottoman in English) in honour of Osman.
The sultan was the sole and absolute regent, head of state and head of government of the empire, at least officially, though often much power shifted de facto to other officials (in principle all his subservient creatures), especially the Grand Vizier, after whose palace the Ottoman government was known as High Porte, the Sultan's own Topkapı Palace being mainly a seraglio, 'harem'.
See the article on state organisation of the Ottoman Empire for further information on the sultan and the structure of power.
The Ottoman Empire or Ottoman State (Ottoman Turkish: دولتْ علیّه عثمانیّه Devlet-i Âliye-yi Osmâniyye, Modern Turkish: Osmanlı İmparatorluğu or Osmanlı Devleti), also known by its contemporaries as the Turkish Empire or Turkey (see the other names of the Ottoman State), was an empire that lasted from 1299 to November 1, 1922 (as an imperial monarchy) or July 24, 1923 (de jure, as a state). It was succeeded by the Republic of Turkey, which was officially proclaimed on October 29, 1923.
At the height of its power (16th–17th century), it spanned three continents, controlling much of Southeastern Europe, Western Asia and North Africa. The Ottoman Empire contained 29 provinces and numerous vassal states, some of which were later absorbed into the empire, while others gained various types of autonomy during the course of centuries. The empire also temporarily gained authority over distant overseas lands through declarations of allegiance to the Ottoman Sultan and Caliph, such as the declaration by the Sultan of Aceh in 1565; or through the temporary acquisitions of islands in the Atlantic Ocean, such as Lanzarote (1585).
The empire was at the centre of interactions between the Eastern and Western worlds for six centuries. With Constantinople (Istanbul) as its capital city, and vast control of lands around the eastern Mediterranean during the reign of Suleyman the Magnificent (ruled 1520 to 1566), the Ottoman Empire was, in many respects, an Islamic successor to the Eastern Roman (Byzantine) Empire.