Who or what is included in each branch of US government?

Assuming you're referring to the branches of government in the U.S.A., there are three of them. The Executive Branch includes the Office of the President and an enormous array of federal agencies such as the Food and Drug Administration, the Federal Bureau of Investigation, the Department of Homeland Security, and many, many more. These federal agencies all answer (at least theoretically) to the Office of President, and collectively they are considered all part of the Executive Branch. The Legislative Branch includes the the Senate and the House of Representatives. There are a small number of agencies that are also part of the Legislative Branch, such as the Government Accountability Office, which, though it is a government agency, answers to the House of Representatives rather than the Office of the President. The Judicial Branch includes the Supreme Court and the Federal Court System, which includes federal judges and their support staff.