The leadership of Ravnica is shared by the guildmasters of the ten guilds in charge of Ravnica. Through magic known as the Guildpact, each guild serves a specific function within and for Ravnican society and cannot be removed from their position.
Over the millennia, the guilds' intended purposes and their actual functions have altered. They have built up entire cultures and are an intrinsic part of life in Ravnica, even to those who are not formal members of any guild.