Most people know that the Iowa caucus occurs in February. But many are confused as to how a caucus is different than a primary, and how the caucus process actually works for each political party.
Each state is assigned a certain number of party delegates, based upon population figures. The delegates chosen will get to attend the national convention for their party, and vote in the nomination process for the Presidential election.
Most states, including New Hampshire, select delegates to the parties' national conventions by holding primaries. Primaries are simple votes in which attendees vote for their candidate, and delegates are decided based on the percentage of votes each candidate receives.
Iowa, however, does things differently. In february, Iowa holds its caucus, the process of which has been compared to a 'town hall meeting', at least for Democrats. Each party is allowed to conduct its state primaries or caucuses based upon its own rules.
Each of the state's precincts has a meeting place, usually a school or a library, and any registered member of each party is allowed to attend that party's caucus meeting. While these caucuses are actually held every two years, the storm of media focus is centered on the years in which Presidential candidate delegates are chosen.
For Republicans in Iowa, each voter casts a vote by writing the name of his or her chosen candidate onto a blank piece of paper. The results are tallied and reported to the press. However, the delegates are not necessarily chosen based on how many votes each candidate received, but by the caucus as a whole after the votes are taken.
It's a different story for Democrats. The caucus for them begins with tables or corners designated for each candidate, and sometimes a separate area for 'undecided' voters. For 30 minutes, members of each group try to convince each other (especially the 'undecideds') to switch support to their candidate.
After 30 minutes, a head count is taken for each group. For a candidate to receive any delegates, he or she must be considered 'viable'. This means that, any particular candidate must receive a certain percentage (usually 15 - 25%) of the total votes in the room, which varies depending on the number of total delegates available in ratio to caucus attendees.
If a candidate is determined to be not viable, his or her supporters must disband. They can join another candidate's group, remain undecided, or abstain. Another 30 minutes are allowed for realignment (and more convincing) to occur.
This realignment process is considered important to the Democratic party in Iowa, because attendees' second choices become much more important than in the Republican process.
After a second head count is taken, delegates are awarded to the remaining viable candidates based upon the percentage of supporters each garnered. Delegates then go to the county convention, where they vote for delegates to attend the district and state conventions.
The heavy focus on Iowa remains due to its early date. It is considered first real measure of which candidates will later succeed or fail at national level. While results in Iowa have not always predicted a later party winner, the victor in each party at this level will get more press time, and seen by public as leader, an important factor in the process.