A triumph for Clinton and Trump: everything you need to know about Super Tuesday.

If you’ve been following the circus that is the US presidential nominations (or even if you tried to block your ears to them about the time Donald Trump called Mexicans “killers and rapists”) you’ve probably seen a bunch of headlines shouting about Super Tuesday today.

Super Tuesday is a massive step in the race for the presidential nomination in the US — and because of its implications for global politics, it’s being closely followed in Australia too.

As Americans take to the polls, we answer your burning questions about what Super Tuesday involves, and why you should care.

Back up. What even is Super Tuesday?

It’s a day that forms an important part of the nominating process of United States presidential elections.

Normally, primary votes are staggered from about late January until mid-June. But on Super Tuesday, Americans cast primary votes in about a dozen states at once. Because so many votes take place at once, this single day has the power to end or massively boost a candidacy.

Here's how it works (and this is where it can get confusing for the uninitiated reader): Voters on Super Tuesday don't directly select a particular person to run for president. Instead, they determine delegates from their state and those delegates, in turn, select their party's presidential nominee.

To win a party's nomination, a candidate must collect a majority of delegates (The Guardian describes delegates like gold coins that candidates have to collect. Cute, hey?) According to the Congressional Research Service, this means the Democratic candidate needs a total of 2,382 delegates and the Republican candidate needs 1,236 to secure their party's nomination.

On Super Tuesday alone, Democrats are competing for a total of 865 delegates, while Republicans are competing for 595 delegates, Daily Dot reports.

What states are voting today?

This year, Super Tuesday is weighted heavily in the south: the participating states are Alabama, Alaska, Arkansas, Colorado, Georgia, Massachusetts, Minnesota, Oklahoma, Tennessee, Texas, Vermont, Virginia... Plus the territory of American Samoa.

 Why does it matter?

Super Tuesday will make clear whether Senators Ted Cruz, Marco Rubio and Bernie Sanders are "viable challengers or distant threats to frontrunners Hillary Clinton (D) and Donald Trump (R)," as the Daily Dot puts it. Plus, the day is often seen as the first real test of national electability because it "represents a more geographically and demographically diverse swath of states than we've seen the 2016 presidential field encounter so far," Daily Dot reports.

That said, we can't put too much weight on the results of Super Tuesday. As Kicker explains, we will get a clearer picture of who the presidential nominees will be today, but the result of the actual election in November is still going to be unclear. That's because "Super Tuesday states usually lean one way or the other, either Republican or Democratic.... So if, say, Hillary Clinton wins the Democratic primary in Texas, she probably won't win Texas in November. "

Who's winning so far?

Billionaire entrepreneur and reality TV show host Donald Trump has bounced back from his loss in Iowa to perform well in Super Tuesday, which effectively makes him the Republicans’ presumptive nominee. However, Real Clear Politics polling averages suggest that Ted Cruz has about a 10 point lead over Trump in his home state of Texas. Texas has the biggest group of delegates up for grabs on Super Tuesday, so that state's results really matter.

On the Democratic side, Hillary Clinton has done well. She "effectively tied Bernie Sanders in Iowa and lost big to him in New Hampshire, but then beat him convincingly in Nevada before trouncing him by an astonishing 47% in South Carolina," Landman writes.

The prominent role of African-American voters in the southern Super Tuesday states (such as South Carolina) appears to have helped Clinton, who leads Bernie sanders in polls of non-white voters, The Guardian reports.