How did Athens develop democracy under Cleisthenes in 507 BCE?

In 508–507 BCE, Cleisthenes transformed the Athenian government by shifting the basis of political organization from hereditary kinship to locality, effectively dismantling the power of noble clans.1

To achieve this, he implemented several key reforms:

• Deme-based Citizenship: Public rights and duties were tied to membership in a deme (township), which maintained its own citizen register and elected local officials.1
• Reorganized Tribes: He replaced the four traditional blood-based tribes with ten new local tribes. To prevent factionalism, each tribe was composed of townships from three distinct areas: the city, the coast, and the inland region.1
• Expanded Representation: The Council of Five Hundred was established, with 50 members selected from each of the ten new tribes, ensuring broader participation in public life.1
• Isonomia: These reforms promoted isonomia, or equality of rights for all citizens, fostering more active public engagement.1

Additionally, tradition credits Cleisthenes with introducing ostracism, a political practice designed to protect the state by banishing individuals who threatened its stability.23