Rule by a single signore (lord), often gaining power via military conquest or political instability. Supported by a small circle of advisors and mercenaries. Common in northern Italy (13th–14th centuries). Famous examples: Visconti (Milan), Medici (Florence), Sforza (Milan).
Rule by a council of citizens (elected), with power shared among factions/guilds. Prevalent in central/southern Italy (12th–13th centuries). Often clashed with signorias and rival city-states.
Both systems provided frameworks for political/economic growth and fostered civic identity.