[Note: This is the first in an occasional series, Remedial Civics, which provides information on what you should have learned in school—but probably didn’t—about how the U.S. government works (or doesn’t).]

The Congress of the United States is a bicameral legislature, which means that it is made up of two chambers, or houses: the Senate and the House of Representatives. Here are some of the basic facts you should know about who they are and how they are elected.

Congress members are Representatives and Senators . . .

A member of Congress is a U.S. Representative, who serves in the House of Representatives, or a U.S. Senator, who serves in the Senate. A Member of the House also is called a Congresswoman or Congressman. These members have full voting rights.

. . . But also Delegates and a Resident Commissioner.

Along with Representatives and Senators, there are also Delegates (House) and a Resident Commissioner (Senate).

The office of Delegate was established by ordinance of the Continental Congress and confirmed by a law of the U.S. Congress. From the beginning of the Republic, the U.S. House of Representatives has admitted Delegates from territories or districts organized by law. Currently there five Delegates, including one from the District of Columbia, and one from each of the territories of American Samoa, Guam, the Commonwealth of the Northern Mariana Islands, and the Virgin Islands.

Congress created the position of Resident Commissioner in 1900 to apply to Puerto Rico, and later for the Philippines several years later. Only Puerto Rico has had a Resident Commission now, since the Philippines became independent in 1946.

Delegates serve a two-year term and the Resident Commissioner serves a four-year term. They have much the same authority as their other members. On the House Floor, they can speak, introduce bills, and offer amendments. They also can serve on House Committees and possess most of the authority that other Committee members have.

Delegates and the Resident Commissioner also may offer amendments while the House is conducting business as the Committee of the Whole House on the state of the Union. However, unlike Representatives and Senators, they may not vote while the House is conducting business as the Committee of the Whole or vote on the final passage of legislation when the House is meeting.

Voters decide who will serve in Congress . . .

Members of the House serve two-year terms and Senators serve six-year terms.

Because national elections take place every even-numbered year, one third of the Senate and the entire House are up for election every other year.

The Constitution (Article I, section 3) originally said that senators were to be chosen by their state legislature. However, in 1913 the 17th Amendment to the Constitution was ratified, allowing for the direct election of senators. Today, though, individual voters vote to directly elect members of both the House and Senate.

House members are elected by plurality vote (the largest number of votes received) in the congressional district in which they are candidates. Special cases include Alabama, Arkansas, Georgia, Mississippi, North Carolina, Oklahoma, South Carolina, and Texas, which require that a candidate receive a majority (more than half) of popular votes to be nominated. In these states, a runoff primary election between the top two candidates is held if no candidate receives a majority in the first primary.

And Louisiana requires all pete in an “open primary,” an all-party primary election. The candidate who wins the majority (more than half) of the votes is declared elected. The election is held on general election day (the first Tuesday after the first Monday in November). If necessary, a runoff election between the top two finishers will follow several weeks later.

. . . Unless their state’s governor does.

Sometimes, though, members of Congress don’t finish their full term. Since 1973, 84 Members of Congress—69 Representatives and 15 Senators—have died in office. Since 1974, 47 Senators and dozens of Representatives have resigned from office.

If a vacancy occurs due to a senator’s death, resignation, or expulsion, the 17th Amendment of the Constitution allows state legislatures to empower the governor to appoint a replacement plete the term or to hold office until a special election can take place. Typically, a replacement holds office until the next scheduled statewide election. That means the state’s governor can have, at least temporarily, considerable power over who will represent their state in the U.S. Congress.

The law concerning members elected to fill vacancies varies according to when the vacancy occurs and applicable state law. All states, territories, and districts require special elections to fill any vacant House seats during the first session of a Congress.

During the second session of a Congress, however, procedures often vary depending on the amount of time between the vacancy and the next general election. Section 8 of Title 2, United States Code, provides that a state governor can cause a special election in extraordinary circumstances; namely, a crisis in which the number of House vacancies exceeds 100.

Since 1791 there have been 1,494 special elections, with 206 of those since 1970.

You’re stuck with them until the next election . . .

The person your state elects to Congress isn’t likely to be removed, even for bad conduct. Since 1789, the Senate has expelled only fifteen of its entire membership. The last senator to be expelled was Jesse D. Bright (D-IN) in 1862 for supporting the Confederate rebellion. (In 1995, Robert W. Packwood (R-OR) resigned before he could be expelled for sexual misconduct and abuse of power.)

Surprisingly, the House is even less likely to expel its members even though it has more than the Senate. Only 5 members have been expelled, with the ing in 2002 when Jim Traficant (D-OH) was booted after he was convicted on numerous counts of bribery, racketeering, and tax evasion.

. . . And likely after the next election too.

Once elected, they tend to stay elected. Since 1984, incumbent members of the House have won 80 percent of election, and over 90 percent since 2012. Senate races have historically been more volatile, but incumbent election rates have remained over 79 percent since 1988.

The official requirements to hold the offices are minimal . . .

The required qualifications are found in Article 1 of the Constitution are that members of the House of Representatives must be 25 years of age, a citizen of the United States for at least 7 years, and be a resident of the state at the time of election. To be a U.S. Senator, a person must be 30 years of age, a citizen of the United States for 9 years, and be a resident of the state at the time of election.

. . . Even more minimal than you might realize.

While a member have House has to live within the state in which they are elected, they do not have to live in the district in which they are elected. For example, a woman could be elected to represent Texas’s 16th congressional district (El Paso) and live in Texarkana— 810 miles away. And states can’t change that requirement.

In 1995 case U.S. Term Limits, Inc. v. Thornton, the U.S. Supreme Court ruled that “qualifications clauses were intended to preclude the states from exercising any [power over Congressional requirements]” and, as a result, the Constitution “fix[es] as exclusive the qualifications in the Constitution.” This decision nullified the law in 23 states that also established term limits for their members of Congress.

Currently, nearly two-dozen members of the House that live outside of their congressional districts.

The Constitution also does not require the Speaker of the House to be a member of the House, though to date all Speakers have been members.