As you await tonight's caucuses, allow me to make a humble suggestion: Get up to speed on everything you need to know to interpret the results by listening to the latest 538 Politics podcast. After the final pre-Iowa debate — the cycle's first head-to-head faceoff between Haley and DeSantis — my colleagues Nathaniel Rakich, Leah Askarinam and Elliott Morris sat down with me to talk about what we'd watched and what to expect coming into tonight. We had some fun too!

Generally speaking, a caucus is an event where party members gather to conduct party business. In a presidential year, that can include electing delegates to the next step of the multilevel national delegate election process — that is, the selection of the actual people who will go to the county convention, which then picks delegates for the state convention, where the national delegates are then chosen. How a caucus functions depends on the state and the party's rules. In some states, like Iowa, a caucus includes a presidential vote by participants that allocates national delegate slots to candidates that are then filled by the selection process. In others, the state party may use a caucus-convention system to select the individuals who'll serve as delegates, but actually allocate national delegate slots using the state's presidential primary.

Today in Iowa, Republicans are holding precinct caucuses to begin their national delegate selection process (Iowa Democrats will also hold them, but no longer use them to allocate national delegates). Run by the party, the GOP meetings take place in the evening at government centers, schools, churches, businesses and even homes. Prior to the preference vote, the caucus chair at each caucus will invite one attendee each to speak on behalf of each of the candidates. Then, each attendee casts a presidential preference vote, which gets reported to the wider world. The results of these votes statewide will determine how the state's 40 national delegates are allocated. (Before 2016, this much-watched vote was actually non-binding and played no direct role in the Republican allocation process.) Following the preference vote, attendees can stay to participate in party business, including electing precinct committee members and selecting county convention delegates.

While most states hold primaries, Iowa Republicans are not alone in using a caucus vote to allocate delegates: Seven states lack a presidential primary law, and most territories use a caucus-convention or other party-run event, too. Even in primary states, a party can forgo an available primary option to allocate delegates with a party-organized event, such as a caucus or party-run primary. Nevada is a prominent example this cycle: There, the state GOP opted to use caucuses on Feb. 8 to allocate delegates instead of the state's primary on Feb. 6, although a Republican primary will still occur.

According to the polls, Trump is on his way to a huge win in Iowa, while Haley and DeSantis are in a close race for second place. As of 9 a.m. Eastern this morning, when we ran our Iowa polling average for the last time, Trump was polling at 53 percent on average, Haley was at 19 percent, DeSantis was at 16 percent, Ramaswamy was at 6 percent and Hutchinson was at 1 percent.

Believe it or not, though, Trump's lead is even bigger nationwide. According to our national polling average as of 2 p.m. Eastern, Trump was at 63 percent, Haley and DeSantis were at 12 percent each, Ramaswamy was at 4 percent and Hutchinson was at 1 percent.

In other words, Trump is sitting pretty.

Iowa's ready for its close-up. This evening, eyes across the nation will turn to the Hawkeye State, as Republican caucusgoers finally cast the first votes of the 2024 presidential primary contest.

We probably don't need to tell you this, but the race so far has been less than suspenseful, with former President Donald Trump maintaining a commanding lead in the polls throughout the campaign. But his competitors have been campaigning hard to keep their presidential bids alive.

Former U.N. Ambassador Nikki Haley is sitting in (a distant) second place after a late surge in the polls and may benefit from the recent exit of staunchly anti-Trump former New Jersey Gov. Chris Christie. She's pinned her hopes primarily on next week's contest in New Hampshire, but a strong showing tonight could confirm that her momentum is real. Florida Gov. Ron DeSantis, on the other hand, has gone all in on Iowa. He's racked up some high-profile endorsements in the state and has an ambitious ground game, but it remains to be seen if he'll be able to peel off support from some of the same support bases as Trump: rural and evangelical voters. Entrepreneur Vivek Ramaswamy has similarly focused on Iowa, but an eye-catching number of campaign events in the state hasn't lifted him above the mid-single digits in the polls since August.

Another big question mark heading into today is the weather: A blizzard ground the last few days of campaigning to a halt and Iowans will need to brave harsh winter conditions and below-zero temperatures to make it to their local caucuses.

As for the nuts and bolts, caucuses will begin at 7 p.m. Central time. The first results are expected around 7:30 p.m. Central, and they'll continue to trickle in over the next few hours. In the past, winners in Iowa have been projected as soon as 90 minutes after caucuses began and as late as ... well, never. But given Trump's huge polling lead and the GOP's concerted efforts to ensure a smooth reporting process, we expect tonight's contest to wrap up on the earlier end of the spectrum.

The team from 538 will be here all evening bringing you live results and analysis as we see which candidates emerge with the delegates, the winning narratives and the snow-hardiest supporters. So keep this page open!