In ancient Rome, the fasti (Latin plural) were chronological or calendar-based lists, or other diachronic records or plans of official and religiously sanctioned events. After Rome's decline, the word fasti continued to be used for similar records in Christian Europe and later Western culture.
Public business, including the official business of the Roman state, had to be transacted on dies fasti, "allowed days". The fasti were the records of this business. In addition to the word's general sense, there were fasti that recorded specific kinds of events, such as the fasti triumphales, lists of triumphs celebrated by Roman generals. The divisions of time used in the fasti were based on the Roman calendar.
The yearly records of the fasti encouraged the writing of history in the form of chronological annales, "annals," which in turn influenced the development of Roman historiography.
Fasti is the plural of the Latin adjective fastus, most commonly used as a substantive. The word derives from fas, meaning "that which is permitted," that is, "that which is legitimate in the eyes of the gods." Fasti dies were the days on which business might be transacted without impiety, in contrast to dies nefasti, days on which assemblies and courts could not convene. The word fasti itself came to denote lists organized by time. The temporal structure distinguished fasti from regesta, which were simple lists of property, or assets, such as land or documents, or transactions transferring property.
Fasti Magistrales, Annales or Historici, were concerned with the several festivals, and everything relating to religious practice and the gods, and the magistrates; to the emperors, their birthdays, offices, days consecrated to them, with feasts and ceremonies established in their honor or for their prosperity. They came to be denominated magni, "great," by way of distinction from the bare calendar, or fasti diurni ("everyday records"). The word fasti thus came to be used in the general sense of annals or historical records.