Hardly anyone in the US really understands what the difference is between caucuses and primaries and how the rules of the Democrats and those of the Republicans differ. But everyone knows that it's the Iowa caucus and New Hampshire primary that decide the future of those hoping to be nominated by their respective parties as their presidential candidates.

For someone who did not grow up with the system, it is hard to understand why such an important role is played by Iowa, a small state in which only 1 percent of the US population lives, where there are four times more pigs than humans and which is responsible for every fifth ear of corn. This is where the official battle for the presidential nominations begins on February 1.

Small primaries with huge significance

Why these first elections in Iowa and New Hampshire play such a role is almost a philosophical question. Are they so important because often they anticipate the direction all the caucuses and primaries will take? Or are they so important because the results of the people who participate are taken so seriously that they decide on the direction of the months to come?

The answer to this question might only be really meaningful to philosophers. But the candidates know that those of them who do not fare well will not be able to catch up later on in the campaign, especially not in this strange election year. Failure to win in either state can mean a very abrupt end. But why?

Wooing the voters

In these elections, candidates have to prove that they are electable. They have to prove not only that they are capable of raising funds and attracting influential supporters to their side but also that they can woo the voters. They have to prove that they can win not only the polls but the people. They have to prove that they can match expectations - not only in appearance, but in reality. This is perhaps what is most important in this massive media show.

Trump does not go down well everywhere

Of course, expectations differ according to candidate. Let's begin with Donald Trump: He has been shaping how the media perceive the Republicans for over six months. In defiance of all the commentators and despite his unsettling public appearances, he is headline news. If the polls are to be believed, people like him because he has understood how to position himself as an outsider, as someone who cannot be corrupted, who can be believed. Most of all, he has sold himself as a man who knows how to win.

And that's exactly why Iowa could be his undoing. Iowa is small, very white and very religious. It has a population of god-fearing farmers who might not like smug and bawdy jokes. They might not like the Trump show. Sarah Palin, whom the New York multi-millionaire recently conjured from under his hat to win over the religious working classes, might not quite do the trick.

What would happen then? What happens to someone who keeps banging on about his winner status if he loses? Would he give up? This is foreseeable. Trump's rivals in the party would know what to do. The Republican establishment hates him so much that even the billionaire and former New York mayor Michael Bloomberg is thinking of running if he wins the Republican nomination and Bernie Sanders wins that of the Democrats.

What about the Democrats?

Bernie Sanders is the provocative candidate on the other end of the spectrum. Just weeks ago it seemed impossible that this unknown, self-proclaimed socialist could have a serious chance against the Clinton dynasty, with Hillary at its head. But once again if the polls are to be believed, this now seems very possible.

What would it mean for Clinton if Sanders won in Iowa? If he succeeded in doing what Barack Obama did in 2008? Obama's advisers later claimed that this victory had laid the path for his nomination. Because the winner gets all the attention and positive coverage, while the loser becomes the object of scorn and people start questioning whether he or she will really make it to the end, when it becomes a matter of voters deciding for themselves and not the machine.

Such doubts are poison for the financial backers, the fans and the undecided voters. History is full of examples of people who have sacrificed their convictions to be on the side of the winner.

Rarely has the prelude to a US election campaign been so highly charged and exciting. Never in modern history has the country been so divided. Bernie Sanders and Donald Trump are the two faces at either extreme of the spectrum.