A form of government which is based on the idea that people can govern themselves is most commonly called

The form of government you are referring to is most commonly called democracy. In a democratic system, the power rests with the people, who exercise that power directly or through elected representatives. The core principle of democracy is the idea that every individual has a voice and a vote in the decision-making process that affects their lives and the governance of their country.

This form of government promotes individual rights and freedoms, allowing citizens to participate actively in political processes, such as voting and running for office. Democracies can take various forms, including direct democracy, where citizens vote on legislation and policy decisions directly, or representative democracy, where they elect representatives to make those decisions on their behalf. The underlying belief in democracy is that it enhances accountability, transparency, and public participation in governance, creating a more equitable society.