Final answer:
The system in which citizens elect representatives to govern on their behalf is known as a representative democracy or a republic, as practiced in the United States.
Step-by-step explanation:
The type of democracy being described where citizens elect representatives to make decisions on their behalf is known as a representative democracy or a republic. In the United States, this system is in place because it is not practical for all citizens to come together to make decisions on every issue, and also there is a philosophical belief that not all voters may have the expertise to make such decisions.
This system also serves to protect the rights of the minority against the potential tyranny of the majority. In a representative democracy, elected officials are responsible for crafting laws, setting policies, and governing on behalf of the people, who have the power to hold these officials accountable through elections.