Final answer:
Athenian democracy, established in the 5th century BCE in the city-state of Athens, was the first known democracy in the world. Its direct form of democracy allowed eligible citizens to vote on laws and was an influence on the development of modern democratic systems.
Step-by-step explanation:
The first institution to embrace democracy and put it into practice was the city-state of Athens around the 5th century BCE. Athenian democracy, though limited, is considered the world's first. Following the visionary reforms in the fifth century, more Athenian citizens could participate in the government, although it was still restricted to about 15% of the population.
The Athenian democracy was a direct form, where citizens voted directly on laws and governmental matters. The system had three branches, and one of these branches practiced this direct democracy. While it was not a completely inclusive system, as it excluded women, slaves, and non-citizens, it laid the groundwork for modern democratic practices that inspired the founders of the United States. The concepts of representative democracy further developed in the Roman Republic, where citizens elected representatives to act on their behalf, shaping the structure of the modern American republic.