The United States Senate is the upper house of the bicameral United States Congress, the lower house being the House of Representatives. The composition and powers of the Senate and the House are established in Article One of the U.S. Constitution.
Each U.S state is represented by two senators, regardless of population. Senators serve staggered six-year terms. The chamber of the United States Senate is located in the north wing of the Capitol, in Washington, D.C., the national capital. The House of Representatives convenes in the south wing of the same building.
The Senate has several exclusive powers not granted to the House, including consenting to treaties as a precondition to their ratification and consenting or confirmation of appointments of Cabinet secretaries, federal judges, other federal executive officials, military officers and other federal uniformed officers, as well as trying federal officials impeached by the House.
The Senate is a more deliberative body than the House of Representatives because the Senate is smaller and its members serve longer terms, allowing for a more collegial and less partisan atmosphere that is more insulated from public opinion than the House. The Senate is considered a more prestigious body than the House of Representatives because of its longer terms, smaller membership, and larger constituencies.
This above definition is sourced from Wikipedia, the free encyclopedia: http://en.wikipedia.org/wiki/United_States_Senate
The U.S. Senate also has its own, information-rich website: http://www.senate.gov/
If you would like to learn more about the U.S. Senate, check out this section: http://www.senate.gov/artandhistory/history/common/briefing/Constitution_Senate.htm