All senators serve terms of six years. These terms are staggered in such a way that approximately one-third of the seats in the Senate are up for election every two years.
House of Representatives Terms
All Representatives and Delegates serve two year terms, and the Resident Commissioner serves a four year term.
Sessions
Each Congress lasts for two years and is comprised of two sessions. There are four different types of sessions:
Regular sessions: The House and Senate are in normal operation during the course of the year.
Closed sessions: Only legislators are present to discuss the most important matters, including impeachment of the president, national security concerns or other sensitive information.
Joint sessions: Both houses are present; these occur when the president gives his State of the Union address or otherwise appears in front of Congress. They are also held to conduct formal business or to count electoral college votes in a presidential election.
"Lame duck" sessions: These occur between the elections in November and before the inaugurations in January, when some representatives are about to leave office either by choice or because they were not reelected.