The purpose of the Executive Office of the President is to house the president's advisers and administrative support. Administrative support roles include financial management, personnel management, data processing, and maintenance of records and supply of information. This office also provides general office services, including word processing, mail processing, messenger services and other general needs of the president, his advisers and staff.
The Executive Office of the President includes a variety of councils and departments. The Council of Economic Advisers, Council on Environmental Equality, Office of the Vice President, Office of Management and Budget, Office of Administration and Office of the United States Trade Representative are all contained within the Executive Office of the President. The president's residential staff is also contained under this umbrella.
Several policy offices are also represented in the organization, including the Office of Science and Technology Policy and the Office of National Drug Control Policy. The White House Office staff is included in the Executive Office of the President. The official leader for this entire branch is the White House Chief of Staff, who is traditionally one of the president's closest advisers and reports directly to the president. The Executive Office of the President is responsible for providing the president and his staff and advisers with everything necessary to govern the country effectively.