"Exactly how is the Speaker of the House chosen? Same for the Senate majority and minority leaders." – Larry Kelley, Riviera Beach, Fla.

The Speaker of House is elected by a roll call vote in the House every two years, on the first day of each new Congress. He or she is elected to serve for two years, until the next Congress is installed after a midterm election.

In order to win the speakership, he or she must win an absolute majority of the votes cast. Generally, it is the House majority leader who steps into this role when the position becomes available, however there are no rules dictating this pattern.

In fact, the Constitution does not even specify that the Speaker has to be a Member of Congress, although everyone elected thus far has been.

In modern times, the Speaker serves several purposes in the House, though the Constitution is very vague in defining the role, and the Speakers' responsibilities have changed throughout history.

Today, the Speaker is expected to be the leader of his or her party, the leader of the House as a whole, and is still required to represent his or her district as is expected of any other regular member of Congress.

The Speaker is the third in line to run the country in the event that the president and the vice president are unavailable.

The roles of majority and minority leaders in the Senate are even less defined, and according to an explanation on the official Senate Web site , the positions did not become official until the 20th century.

Floor leaders are elected by members of their party in what is known as a "party caucus," or a meeting of party members. The majority and minority leaders are elected with a majority vote of their party’s members, and typically also serve for a two-year term, even though Senators are elected to serve every six years.

The floor leaders are typically responsible for steering legislation through the chamber, acting as party spokesman, and fulfilling duties to their states.

-- Leah Carliner, Congress.org

Correction: An earlier version of this post misstated the length of senators' terms.

Have a question about how Congress works? E-mail editor@congress.org and we'll answer it in our blog.