America will go to the polls in November to vote for the next president of the United States.
In the US, there are only two parties considered by most voters - the Democrats (the liberal, left-of-centre party) and the Republicans (the conservative, right-of-centre party).
The current president, Donald Trump, is standing again as the Republican candidate, and hopes to serve a second term as the 45th president in the White House.
Democrats have not yet chosen a candidate and members have been campaigning for the chance to be their party’s nominee.
What are primary elections?
Democrat presidential hopefuls are battling for their party's nomination in primary elections – otherwise known as primaries - across different states in the US.
State governments run primary elections, not the parties, and individual state laws determine if the primaries are closed (meaning only registered members can vote) or open (where unaffiliated voters can also participate).
If a candidate wins a primary election, they either win all or part of the state’s delegates.
These delegates will then vote for them at the party convention where the nominee is officially named.
This system was first widely used in the 1970s – previously, party members made the decision at the convention.
What are superdelegates?
In the Democratic primaries there are 3,979 delegates available and if any one candidate wins more than 50 percent of those delegates during a primary season they become nominee in a vote at the convention.
But if it gets to the Democratic convention and no-one has more than half of the delegates, it becomes a contested convention.
In this situation a second vote would follow.
All 3,979 delegates would vote again but would be joined by roughly 771 superdelegates. These are senior party officials including senators, members of Congress, and governors who are free to vote for whomever they wish.
If a candidate then gets 50 percent in the second round then they become nominee.
It is the first time that superdelegates are joining the vote at the second stage and prior to 2020, they could vote at the start of the convention.
This amendment was introduced after Bernie Sanders (see more on him later) campaigned to change the process after he lost out to Hillary Clinton in 2016.
What are caucuses?
A few states have caucuses instead of primaries.
Caucuses are run by parties in regions across the state.
As they are not state government-run, they are more flexible than primaries especially when it comes down to who can take part.
At Democratic caucuses, votes are determined by standing in groups around the room and no ballots are cast.
Who are the main Democratic contenders?
Voters will be choosing between moderate liberals such as former Vice-President Joe Biden and mayor Pete Buttigieg and progressive candidates such as Senators Bernie Sanders and Elizabeth Warren.
- Joe Bidden is an American politician who severed as the 47th vice president between 2009 and 2017. He also represented Delaware in the Senate between 1973 and 2009.
- Michael Bloomberg is an American politician who served as the Mayor of New York for three consecutive terms between 2002 and 2013.
- Pete Buttigieg is an American politician who served as mayor of South Bend, Indiana, from 2012 to 2020. Before running for office he worked on political campaigns for other Democrats.
- Amy Klobuchar has been a Senator for Minnesota since 2007. She previously worked as a corporate lawyer and was a partner at a law firm.
- Bernie Sanders is a Senator for Vermont and has represented the region since 2007. His previous 16 years in the House of Representatives makes him the longest serving independent member of Congress in American history.
- Elizabeth Warren has been a Senator for Massachusetts since 2013. Before that she was a professor specialising in bankruptcy law.
What is Super Tuesday?
This year Super Tuesday falls on March 3.
It's the day when most states and territories hold their primary elections or caucuses.
Some of the more popular states will hold their elections on Super Tuesday, including California and Texas.
How long do primaries go on for?
Primaries and caucuses run between February and June.
However, it is likely the Democrat candidate will be known before as they gather delegates.
When will the Democrat candidate be announced?
The Democratic candidate will be announced at its national convention between July 13 and 16.
The Republican Party will formally announce its candidate at its convention between August 24 and 27.
