The Iowa caucuses are all the hullabaloo in politics these days. Monday's events will be a benchmark for the candidate that may emerge as the leader in the Democratic race to win the nomination to run against President Bush in November.

But understanding the nuts and bolts of the caucuses can be a little mind-boggling.

First off, the word "caucus" is a North American Indian word, thought to be of Algonquin (search) origin, meaning a gathering of the ruling tribal chiefs. The definition used in the American lexicon describes caucuses (search) as a process of political party members gathering to make policy decisions and to select candidates.

A caucus is a small convention — a group of meetings — where party members meet in school cafeterias, living rooms or auditoriums and listen to speeches in public places and vote for delegates to support and represent a candidate at the national convention.

"A caucus is a meeting — it's a neighborhood meeting," said Des Moines Register political columnist David Yepsen.

primary (search), which is the other method states most often use to nominate presidential candidates, is similar to the general election, where qualified voters cast a ballot at the polls to nominate candidates for office.  Each state has its own law for determining whether a primary or caucus will be used to nominate the candidates.

The Iowa caucuses are vital — they are the first step in presidential nominating processes for both the Democratic and Republican parties. The caucuses are also the first step in selecting delegates; county conventions and district conventions follow. The state conventions come later.

The Iowa caucuses are watched by the nation to determine how well candidates are doing with grassroots voters. Traditionally, one of the top three candidates to come out of Iowa goes on to win his party's nomination.

Any registered Iowa resident who is either Republican or Democrat can participate in his or her party's caucus. A little more than 1 percent of the delegates at either party's national convention are from Iowa.

Coming out of Iowa with a decent amount of success requires candidates to develop strong grassroots organizations in Iowa's 99 counties and to encourage voters to turn up for caucus night.

GOP caucus-goers vote for their candidate by ballot.

Democratic participants, on the other hand, raise their hands, use a sign-in sheet or divide themselves into groups depending on for whom they're voting.

Iowa has 1,997 precincts. The first step in the Democratic caucus is to deal with "housekeeping" issues, such as reading letters from endorsers and collecting money to help pay for the caucus.

"Democracy is never cheap and neither are the caucuses," said caucus expert Paulee Lipsman.

Caucus attendees are then broken up into preference groups based on whom they want to vote for. For example, at Monday's event, all supporters of Howard Dean will go to one corner; John Kerry supporters will go in another and so on. Retired Army Gen. Wesley Clark and Connecticut Sen. Joe Lieberman are not participating in the caucuses.

A candidate needs to receive at least 15 percent of total attendees' votes to be considered a "viable" candidate in that caucus and move on to the county convention. If a candidate doesn't get that 15 percent, a "realignment" stage occurs where party voters in that preference group can switch alliances with a different candidate and others can try to convince the fence-sitters whose camp they should join.

"People will actually try to get their friends and neighbors to try to join their presidential preference group," said Gordon Fisher, chairman of the Iowa Democratic Party (search).

It's possible that some candidates may have zero delegates at the end of the night if they can't garner that 15 percent.

"The delegates are then elected from those preference groups that were viable and each precinct is allocated a number of delegates ... and there's a mathematical formula to determine how many each viable delegate presidential group will get," Lipsman said.

Based on the size of the preference groups, the delegates to the county conventions are chosen. One delegate and one alternate can be chosen from every 174 registered voters in each precinct. Then, the party building begins, where committee members are chosen to help report party results at later conventions.

Fifty-six delegates from Iowa represent the state at the national convention. Of the 4,322 Democratic delegates representing the states and territories, the eventual Democratic nominee must earn 2,162.

Some form of caucus has existed in Iowa since the early 1800s, even before Iowa became a state in 1846. The framers of the Iowa constitution allegedly chose caucuses rather than primaries to nominate candidates because they preferred the grassroots democracy approach.

In the early 1970s, the Iowa Democratic Party made several reforms to its delegate selection process, including a 30-day minimum requirement between precinct caucuses and the county, district and state conventions, and publicizing the events to allow more people to take participate.

When the 1972 Democratic State Convention was scheduled for May 20, the new rules dictated that the precinct caucus would be Jan. 24 — the first statewide test for presidential candidates in the nation. In 1976, the Republican Party of Iowa moved its caucus to the same date as the Democrats. The candidates and national media have observed the Iowa caucuses as the "first in the nation" ever since.

Fox News' Steve Brown contributed to this report.