What is the difference between hard money and soft money? Or between Medicare and Medicaid? These are just a few of the many well-used - but often misunderstood - terms in US politics.
Air war The battle between candidates to get as much advertising on television and radio as possible.
Balancing the ticket When a candidate has won his or her party's presidential nomination, he or she is then obliged to pick a "running-mate", who - if the pair win the election - will become vice-president. The two candidates are then often referred to as "the ticket".
Candidates are often advised to pick a running-mate who "balances the ticket" - that is, one whose qualities make up for the candidate's perceived weaknesses.
So in 2000, George W Bush - who was thought to be relatively young and inexperienced - selected veteran Republican operator Dick Cheney. And in 2004, John Kerry, a New England liberal, picked John Edwards, a southerner with a populist streak.
Ballot initiative A number of US states allow for a procedure known as a ballot initiative, whereby citizens are able to draw up a petition for a proposed change in the law, which - if it gathers enough signatures - is placed before voters in a referendum.
If the change is approved by the voters it then becomes law.
Sometimes, political parties may organise ballot initiatives on controversial issues in an attempt to drive up turnout among their core supporters. For example, in 2004, a number of states held referendums on Republican-initiated ballot initiatives to ban gay marriage.
Ballot initiatives are sometimes referred to as "ballot measures" or "propositions".
Bellwether state A state which, historically, tends to vote for the winning candidate, perhaps because it is - demographically - a microcosm of the country as a whole.
The classic example of a bellwether state is Missouri, which has voted for the winner in every US presidential election since 1904 - except 1956.
The term derives from the name for a sheep which shepherds would fit with a bell. By listening out for this sheep, the bellwether, shepherds were able to locate the position of the entire flock.
Beltway An American term for the orbital highway or ring-road that often surrounds major cities. In political reporting the term generally refers to congressional business undertaken inside the highway surrounding Washington DC - Interstate 495. For example, "a beltway issue" refers to a political issue or debate considered to be of importance only to the political class and of little interest to the general public.
Alternatively, those considered to have a "beltway mentality" are seen as being out of touch with the ordinary voters elsewhere in the country.
Bill of rights The collective term for the first 10 amendments of the US constitution establishing the fundamental rights of individual citizens.
The amendments act as a mutually reinforcing set of rights and limit the powers of federal and state governments. Acts of Congress or laws ruled to be in conflict with these rights - and therefore unconstitutional - may be declared void by the US Supreme Court.
The Bill of Rights arose because only a very few individual rights were specified in the original main body of the constitution.
Blue state A state where people tend to vote for the Democratic Party.
Brokered convention If a single candidate for a party's presidential nomination does not obtain the majority of the votes during the primary and caucus process, or during the first round of voting of the party convention, the convention is described as brokered.
The nomination is decided through further ballots.
There may also be an element of political horse-trading behind closed doors, where a deal is done to nominate a candidate and the brokers of the deal urge their supporters to support this candidate in the next ballot.
Buckley vs Valeo The 1976 Supreme Court decision allowing unlimited spending by individuals or groups who are not standing for election themselves but who wish to support or oppose particular candidates.
The provision does not apply to contributions made by corporations or unions and rules that in any donor situation there must be no co-ordination or consultation with any candidate.
The court's decision in effect overruled two major parts of the 1974 Federal Election Campaign Act which imposed mandatory spending limits on all federal races, and limited independent spending on behalf of federal candidates.
The court ruled that such restrictions violated an individual's First Amendment rights to freedom of expression.
The subsequent rise in "soft money" campaign contributions and "issue ads" led to growing concerns about corruption and the influence of pressure groups in federal election campaigns, culminating in the McCain-Feingold legislation of 2002.
Capitol The seat of Congress in Washington DC.
The Capitol, constructed largely of white marble, is home to both the Senate and House of Representatives as well as various committee and hearing rooms and an art gallery.
The steps of the Capitol building are traditionally the stage for the formal inauguration of presidents in the January following an election year.
The building's famous white dome is crowned with a statue of Freedom.
Most states have their own capitol buildings in the state capital, many of which have a similar design to the building in Washington.
Caucus A private meeting of party members designed to seek agreement on delegates for a state or national nominating convention based on which candidate they wish to support.
Participants in presidential caucus meetings generally elect delegates to county conventions who in turn, at a later date, choose delegates for a state or local congressional convention. The delegates selected are not bound, but usually follow the wishes of caucus-goers. It is at these later meetings that the delegates will usually be chosen for the party's national nominating convention at which the presidential candidate will be declared.
Critics of the caucus system argue that its laborious nature tends to mean it is dominated by political activists, unrepresentative of popular feeling, who will nominate candidates with little real chance of winning.
Just under a dozen states use the system - the number is different according to party.
Citizens United A 2010 Supreme Court ruling that overturned aspects of the McCain-Feingold Act on the use of corporate and union money in elections.
In a controversial 5-4 decision, the Supreme Court ruled that corporations should be viewed the same way as individuals in terms of their First Amendment right to free speech.
Using that rationale, it overturned a ban on corporate and union spending on "electioneering communications" - that is, advertisements broadcast within 60 days of a general election (or 30 days for primary elections), which explicitly mention the name of a candidate.
Now, unions and corporations will be able to directly advertise, right up until election day, as long as they haven't co-ordinated their advertisements with a candidate's campaign.
The ruling maintained the McCain-Feingold Act's ban on corporations and unions directly donating to candidates and political parties, as well as the requirement for ads to disclose their funding sources.
Cloture The procedure to place a time limit on consideration of a bill in the US Senate is known as a cloture.
Under this procedure, the Senate may limit consideration of a pending matter to 30 additional hours, but only by 60 votes of the full (100-member) Senate.
The use of a cloture thus prevents a filibuster - an attempt to infinitely extend debate upon a proposal by making a never-ending speech.
Commander in chief The constitutional role granted to the president as head of the United States' armed forces.
Under Article III of the constitution the president is given authority to lead "the army and the navy of the United States and of the militia of the several states when called into the actual service of the United States."
No president since James Madison in the War of 1812 has personally led troops into battle.
Congress forms the law-making or legislative branch of the US Government as prescribed in Article I, Section I of the US constitution.
It is made up of two houses - the 435-member House of Representatives and 100-member Senate - each of which officially has equal power, if not prestige.
A congressional period lasts two years (or sessions) and begins at noon on 3 January of odd-numbered years.
As well as drafting and implementing laws, Congress can also:
- investigate matters of public concern;
- oversee federal agencies and their programmes;
- declare war;
- approve and ratify treaties;
- regulate commerce;
- increase and decrease taxes;
- print and appropriate money;
- confirm/approve judicial and federal appointments and nominations;
- impeach federal officials including the president and vice-president;
- and override presidential vetoes based on a two-thirds majority in each chamber.
Congressman/woman This term is most often used to refer to a member of the House of Representatives, but it can be used to refer to a member of either of the Houses of Congress - the House of Representatives or the Senate.
Constitution of the United States The fundamental law of the US federal system of government, the US constitution defines the principal organs of government, their jurisdictions and the basic rights of citizens.
It is upheld as the supreme law of the land, meaning all federal and state laws, executive actions and judicial decisions must be consistent with it.
The US constitution is the oldest written national constitution in operation.