The Iowa caucuses are Monday, officially kicking off the 2016 race for the White House.
But why is it such a big deal? Well, for such a small state, it has a lot of influence on the election.
Meanwhile, if you want a rundown on what to expect tonight, check out this story.
What is a caucus?
On Monday at 7 p.m., Iowans from both major parties will head to their caucus precincts (there are 1,681 in the state) to cast a vote in favor of their choice to be the candidate for president.
But the process is kind of quirky, and can take several hours.
It involves what are called delegates –they're the people who later this year will attend official nominating conventions, and vote for which candidate should be the official party nominee, the Council on Foreign Relations explains.
So who gets to go, and who do they vote for? Well that's decided at caucuses. Attendees vote for their preferred candidate, and then the delegates are split up based generally on ratios (so if one candidate gets support from half the voters, they get half the delegates), NBC News says.
How it works for each party
This one is more complicated, and involves state delegates and "viability" thresholds – Vermont Public Radio put together a short video using Legos to help explain how the Iowa caucuses work for Democrats:
The Republicans do their caucus voting more traditionally, though. Each campaign can make a final pitch to try and swing any undecided voters before they cast a secret ballot, CNN explains. The votes are then tallied statewide, and delegates are awarded based on percentages.
As explained above, the votes determine the delegates the state will send to each party's' nominating convention, reports note.
But the Iowa caucuses have a lot more influence than that.
Iowa is first, so it's seen as important
Monday night marks the first time a state's voters weigh in on the presidential nomination, rather than being judged by poll numbers, USA Today explains.
Iowa's caucuses gained national attention in the 1970s for being first in the nation, and since then they've continued to generate media attention and political influence, the Republican Party of Iowa explains on its website.
And all that media attention can make the presidential race "turn on a dime," Vox explains. A recent example of this: Back in 2008, now-President Barack Obama won Iowa, causing him to jump up in the polls and make him competitive with Hillary Clinton.
NRP has a story that goes into detail about why Iowa votes first. Read more here.
Iowa has a lot of influence
Because it's first, the Iowa's caucuses have a lot of influence – they can change the "political world's perceptions of who can win," Vox says.
Results from Iowa (and New Hampshire, which holds the country's first primary in February) give a look at a candidate's popularity, FOX 6 explains, and can influence who stays in the race, who people pay attention to, and who drops out.
Candidates tend to drop out of the race if they do poorly in Iowa or New Hampshire, FOX 6 adds, which can really "shake up" the presidential race, Vox explains. (ABC News touches on the "dropout effect" as well, noting some say Iowa's role is to narrow the field of candidates instead of actually picking the next president.)
Typically only 20 percent of registered voters in each party participate in the Iowa caucuses (that's a little more than 100,000 people from each party), CNN says.
Criticism for Iowa's caucuses
Iowa is touted for its influence on the presidential election, but is it warranted?
Politico recently published a story – titled "How Iowa hijacked our democracy" – criticizing the "inflated status of Iowa." The piece argues it "distorts the political process and leads to bad public policy," noting it is "anti-Democratic, meaningless, even harmful."
Why? Because Iowa doesn't represent the rest of the nation (it's mostly white), participating in the caucus vote is difficult (so there's low voter turnout), and the process of the Democratic caucuses doesn't represent the free system.
Supporters of Iowa's caucuses, including Robert Brownell, a Republican on Polk County, Iowa's governing Board of Supervisors, told the Patch the Iowa caucuses give candidates with less money a chance at being president, adding: "Once Iowa and New Hampshire are over, it's all about the money."
Mike McInerney, a 25-year-old insurance broker in West Des Moines, Iowa, who campaigned for Mitt Romney in 2012, spoke to FiveThirtyEight about those who question the Iowa caucuses relevance. He said:
"But the caucuses mimic what the founding fathers wanted — a community gathering, discussing their views and values, challenging each other and then casting a vote, which kicks off the process of selecting the next leader of the free world. It’s quite an amazing thing that all these years later we still do it that way, and it still has a major impact.”