If you mean branches, they are the Legislative, Judicial and Executive Branches, which correspond to the Congress, Supreme Court and the President, respectively.
The Legislative Branch is collectively called Congress, which is a bicameral branch separated into the House and the Senate. They are responsible for proposing laws.
The head of the Judicial branch is the Supreme Court. Headed by 9 Supreme Justices, they are responsible for judging important cases, yet even more important, they are the leading authority on interpreting the Constitution and making sure passed laws are constitutional.
The final branch is headed by the President of the United States. He may veto laws, (though this can be overturned by majority vote), pardon criminals, and utilize a number of other executive powers under the supervision of the two other branches. He or she is also responsible for international affairs and maintaining the general welfare of the nation.
The system of checks and balances which exists among the three branches ensures, (at least in theory), that one branch does not become too powerful (a reference to times of anti-monarchy, when the documents were written). This system is not perfect, though works (in theory) well enough.
The federal government is separated into three parts: the legislative, executive, and judicial branches. The legislative branch is further split into two more parts, the Senate and the House of Representatives. There is no one entity in control of the federal government.
The three parts of government that are separated in the Constitution are known as the separation of powers. The three branches of the government, legislative, executive, and judicial, each have assigned duties, and each can exercise a series of checks and balances to assure, no one portion of the government usurps the powers of the others.
Name Three partes of government that regularley rely on advice from economists
It has three branches each with jobs.
To the extent that there is a single leader of the US government, the President, as head of the Executive branch of the government, is the leader. Because the US federal government is divided into three equal branches, it could be argued that there is no one leader of the government.