A dynasty (UK: /, US: /) is a sequence of rulers from the same family, usually in the context of a feudal or monarchical system, but sometimes also appearing in elective republics. The dynastic family or lineage may be known as a "house", which may be styled as "royal", "princely", "ducal", "comital", etc., depending upon the chief or present title borne by its members. Historians periodize the histories of many sovereign states, such as Ancient Egypt, the Carolingian Empire and Imperial China, using a framework of successive dynasties. As such, the term "dynasty" may be used to delimit the era during which the family reigned and to describe events, trends, and artifacts of that period ("a Ming-dynasty vase"). The word "dynasty" itself is often dropped from such adjectival references ("a Ming vase").
Until the 19th century, it was taken for granted that a legitimate function of a monarch was to aggrandize his dynasty: that is, to increase the territory, wealth, and power of his family members. The longest-surviving dynasty in the world is the Imperial House of Japan, the Yamato dynasty, whose reign is traditionally dated to 660 BC.
Prior to the 20th century, dynasties throughout the world have traditionally been reckoned patrilineally, such as under the Frankish Salic law. In nations where it was permitted, succession through a daughter usually established a new dynasty in her husband's ruling house. This has changed in some places in Europe, where succession law and convention have maintained dynasties de jure through a female. For example, the House of Windsor is maintained through the children of Queen Elizabeth II, similarly with the monarchy of the Netherlands, whose dynasty remained the House of Orange-Nassau through three successive queens regnant. The earliest such example among the major European monarchies was in Russia in the 18th century, where the name of the House of Romanov was maintained through a non-ruling female.
In South Africa's Limpopo Province, Balobedu determined descent matrilineally, while rulers have at other times adopted the name of their mother's dynasty when coming into her inheritance. Less frequently, a monarchy has alternated or been rotated, in a multidynastic (or polydynastic) system – that is, the most senior living members of parallel dynasties, at any point in time, constitute the line of succession.
The word "dynasty" is sometimes used informally for people who are not rulers but are, for example, members of a family with influence and power in other areas, such as a series of successive owners of a major company. It is also extended to unrelated people, such as major poets of the same school or various rosters of a single sports team.