The three branches of government are:

1. Legislative Branch: Made up of the House of Representatives and the Senate (collectively called Congress), this branch is responsible for making laws, declaring war, regulating commerce, and controlling taxing and spending policies.
2. Executive Branch: Headed by the President, along with advisors and various departments and agencies, this branch is responsible for enforcing the laws passed by the legislative branch.
3. Judicial Branch: Consists of the Supreme Court and other federal courts. This branch interprets laws and ensures they align with the Constitution.

These branches are separate to ensure no single branch becomes too powerful, and they provide a system of checks and balances on each other to protect citizens' rights and maintain effective government. Each branch has defined powers and responsibilities but must work with the others to govern effectively. This three-branch system is established by the U.S. Constitution.