The government of the United States of America is the federal government of the constitutional republic of fifty states that constitute the United States...
All legislative bills for raising revenue must originate in the House of Representatives. The approval of both chambers is required to pass any legislation, which then may only become law by being signed by the President (or, if the President vetoes the bill, both houses of Congress then re-pass the bill, but by a two-thirds majority of each chamber, in which case the bill becomes law without the President's signature).
Article I, Section 2, paragraph 2 of the U.S. Constitution gives each chamber the power to "determine the rules of its proceedings."
The powers of Congress are limited to those enumerated in the Constitution; all other powers are reserved to the states and the people.
http://en.wikipedia.org/wiki/Federal_government_of_the_United_States