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.
National convention The party assembly held every four years at which state delegates from across the country gather to vote on the party's candidate for president and vice-president.
National conventions now serve mainly to formalise the will of the majority of voters, expressed during the earlier state primaries and caucuses. Usually the winner of the greatest number of delegates from the primary and caucus states will receive the party's nomination.
Nonetheless the processes remain in place in case the decision over the party's candidate has to be brokered by the various party leaders. In 1924, a bitterly divided Democratic Party took no less than 103 ballots to decide on their presidential candidate.
Today the event is largely a platform for the prospective candidate to present their choice of vice-presidential running mate and to draw up their policy agenda.
Oval Office The office traditionally occupied by the president in the West Wing of the White House.
The room did not exist until the 1930s when it was added on as part of expansion work to the building. The term is often used to describe the presidency itself, for example: "This order comes straight from the Oval Office."
Patriot Act A law enacted in response to the 11 September attacks giving government agencies new powers to tackle terrorism. The law permits the indefinite imprisonment without trial of foreigners deemed to be a threat to national security.
The government is not required to provide detainees with a lawyer or make any announcement regarding the arrest. The law also extends police powers to wiretap and search a suspect's home.
These and other tough measures included in the law have sparked severe criticisms from liberals who argue that it endangers civil liberties and that its search and detention provisions are unconstitutional. Critics also say the law was passed without proper review in a climate of fear - only one senator voted against it.
Supporters of the law argue that these new powers are essential to prevent the loss of thousands of lives in another terrorist attack on US soil, and that any loss of rights is justified in order to protect the basic right to security.
Political Action Committee (PAC) An organisation formed to promote its members' views on selected issues, usually by raising money that is used to fund candidates who support the group's position.
PACs monitor candidates' voting records, question them on their beliefs on issues of interest to their membership and pass the collected information along to their contributors.
Because federal law restricts the amount of money an individual, corporation or union can give to candidates, PACs have become an important way of funnelling large funds into the political process and influencing elections.
PACs have their origins in the 1940s as a response to restrictions on unions using their money to contribute to federal election campaigns.
The number of PACs exploded following the campaign funding laws introduced in the 1970s, from 608 in 1974 to 4,009 in 1984. Over the same period contributions from PACs rose from $12.5m to $105.3m.
Pork barrel politics The appropriation of government spending - or "pork" - by a lawmaker for projects that are likely to benefit his or her constituents or campaign contributors. (See earmark).
Primary A state-level election held before a general election to nominate a party's candidate for office.
Primaries are held for both the presidential and congressional races, although the exact regulations governing them and the dates on which they are held vary from state to state. In some states voters are restricted to choosing candidates only from the party for which they have registered support.
However 29 states permit "open primaries" in which a voter may opt to back a candidate regardless of their nominal affiliation. In this case strategic voting may take place with, for example, Republicans crossing over to back the perceived weaker Democratic candidate.
Primaries first emerged as a result of the so-called "progressive movement" of the early 20th Century, which argued that leaving the nomination process purely to party bosses was inherently undemocratic.
Pro-choice The term used for those who support a woman's right to choose abortion if she so wishes.
Supporters of the pro-choice agenda do not necessarily support abortion itself, only the position that women are entitled to make the decision themselves. Most pro-choice politicians will usually seek to avoid the emotive issue of abortion itself, following instead the libertarian line that government has no place interfering in what should be a private decision.
The Democratic Party has been broadly supportive of the pro-choice movement. President Clinton summed up his party's stance by saying abortions should be "safe, legal and rare".
Republicans, however, have been divided. The religious right-wing of the party still calls for a total ban on abortion, while moderates are wary that a strong stance will deter female voters from the party. Under George W Bush, the right-wingers have scored an important victory in getting Congress to pass a ban on "partial birth" abortions.
Pro-life The term used to describe politicians and pressure groups opposed to abortion or allowing women to opt for abortion.
Some American advocates of the pro-life position believe abortion should only be allowed in cases where a pregnancy results from rape or incest. Others believe that abortion should be ruled out altogether.
The 1973 Roe vs Wade verdict by the US Supreme Court, in effect legalising abortion in the US, is viewed by pro-life supporters as in contravention of the fundamental rights of the unborn child.
Purple state Another term for swing state. A state which could vote Democratic (blue) or Republican (red).
Push polling The controversial practice where voters are contacted over the telephone by campaign workers, who talk up their own candidate and rubbish opponents.
Push polling became a prominent feature of the 2000 Republican primary campaign, with candidates George W Bush and John McCain each accusing the other of descending into increasingly dirty campaign tactics.
Voters often say they feel deceived by the technique, particularly as a typical call often begins with the kind of questions that a normal, independent survey would ask. Some observers say the technique undermines voter confidence in the electoral system and risks deterring yet more voters from turning out on polling day.