With the Iowa caucuses just a day away, here are five things to know about the all-important first-in-the-nation presidential nominating contest.

1. Caucus-goers can register on the day of the caucus: Although only registered Republicans can vote in the caucuses, essentially all eligible voters can participate in the Iowa caucuses. How is this possible? Because Iowa allows same-day voter registration. This means that voters - regardless of party affiliation - can register as a Republican on Tuesday evening prior to the caucuses. So, if you're registered with another political party and want to participate, simply re-register before the caucuses, which began at 7 p.m. local time, and you're good to go.

2. Results will come in within an hour: Republicans will caucus at more than 1,700 sites across the state. Here is how it works: each voter casts a single ballot for the presidential candidate they prefer. The total ballots - which are based on the percentage won by each candidate - are phoned in by a caucus official to the state party as soon as the balloting closes. The caucus is usually over within an hour, with the presidential preference poll taking place within the first half hour and the delegate selection taking place in the latter half of the event. (Note: the Democratic caucuses in Iowa operate under a different set of procedures than the Republican caucuses.)

3: What's up for grabs: The state of Iowa has 28 delegates to be seated at the Republican Party's presidential nominating convention, which will take place in Florida later in the year.

4. The Iowa caucuses are actually non-binding: Yes, you read that correctly. The caucuses are not binding and basically serve to measure the preference of Iowa voters at that particular moment. Twenty-five of the delegates will be chosen at the state's nominating convention in June, while the remaining three will be selected by the state chair, national committeeman and national committeewoman (each official get to chose one delegate apiece).

5. The Iowa caucuses are a poor predictor of who will win the presidency: Though Iowa can serve to help a candidate jump-start momentum in the primaries, recent history shows that the caucuses are a not a good indicator of which candidate will win the presidency. Since 1972, only three presidents have won Iowa and the presidency: Barack Obama in 2008, George W. Bush in 2000 and Jimmy Carter in 1976 (note: this figure does not include when the incumbent president is unopposed). Still, the latest polls out of Iowa indicate that the caucuses will be a three-way race between Mitt Romney, Ron Paul and Rick Santorum.