1. What is a caucus?

2. The two main US parties use caucus meetings and primary elections to select a candidate to put forward for the Presidential Election.

3. Although a primary is an event at which party members simply show up and cast their votes, a caucus is much more a political rally than a voting procedure.

4. Iowa's process for choosing between presidential candidates is unique among the fifty United States. Every other state has a more traditional primary election in which registered voters can cast their ballots for the candidates they prefer. In Iowa, however, voters in each political party attend separate, small meetings, or caucuses, in towns and neighborhoods across the state. Caucuses are held at the precinct level in schools, fire stations and sometimes even in individual's homes.

5. How do the Republican caucuses work? Anyone registered with the party can attend the caucus meetings, but only those eligible to vote (i.e. over 18) can participate in the caucus ballot. Where Are the Caucuses? All over the state. There are 1,774 precincts in Iowa, meaning 1,774 churches, libraries and other buildings where caucus-goers will converge Tuesday starting at 7 p.m. central time.

6. It's not just show up and vote. The caucuses are part poll, part GOP meeting. And unlike in a primary, supporters of particular candidates are allowed to campaign on site. In fact, it's part of the process. Before any votes are cast, supporters and surrogates of the various campaigns are permitted a few minutes to make the case for their candidate. This process means it's in every candidate's interest to have a speaker at all 1,774 caucus sites, as a way to sway uncommitted Iowans at the last minute. After the speeches, those in attendance then write down their choice on a piece of paper. The results are counted, announced and fed to the media.

7. What happens next … Tonight’s caucus meetings will select delegates who will then go forward to Iowa’s county conventions (99 of them) in March, at which the Republican Party will choose delegates to go forward to the state convention. Delegates who are selected through the state selection process will meet at a Republican National Convention to cast their votes in support of their candidates which leads to the selection of someone to run for the presidency.

8. How Important Is This Iowa Contest, Anyway? Historically, Iowa does not have the best record of picking winners, at least on the Republican side. In the last five GOP primaries without an incumbent, the winner of the Iowa caucuses went on to win the nomination just two times - in 1996 and 2000. However, political analysts generally agree that it's very important to place roughly in the top three in Iowa. The only GOP nominee since 1972 who did not finish in the top three in Iowa was John McCain in 2008.