By Rajini Vaidyanathan
Political reporter, Radio 1
You can not have escaped the fact that the biggest job in the world is up for grabs - POTUS as they call it. President of the United States of America.
George Bush leaves office next year after eight years in the White House
Although George Bush doesn't hand over the keys to the White House until January 2009, the race to find his replacement has already begun.
Two strikes and you're out
George Bush has been in the job since the year 2000 and by next January he will have served two four year terms in office.
In America that is the maximum time you're allowed to be President for. So like it or not, George Bush has to step down as President.
George W Bush is a Republican. America is a two-party system. You've got the Republicans and the Democrats.
Historically the Republicans have been linked more to the Conservative party, and the Democrats to Labour.
So what is happening now?
Like the super sized donuts and giant bagels - Americans like to do politics big too.
The first step in the Presidential race is deciding which two candidates, one from each party, will go head to head in the big vote in November.
That is what has already started in the primaries and caucuses.
What is a primary or a caucus?
The primaries and caucuses are held in every part of America and are basically mini-popularity contests. People in each state get to decide which two candidates from each party they would prefer as the candidates.
Each state or territory in the US holds either a primary or a caucus.
Primary or caucus?
In a nutshell, a primary is where voters go to the ballot box to cross off who they want as their candidate.
You can only take part in some primaries if you belong to either the Democrat or Republican party.
In other states independent voters are allowed to pick whether they want to have a say in choosing the next Democrat or Republican candidate. But you can't take part in both.
So, you might want a say on the Democrat (Hillary Clinton, Barack Obama) contest.
You might instead fancy casting your vote on who the Republicans are going to choose.
Caucus means meeting. It is where people gather in their local town halls and hear what all the campaigners have to say. Then it's a show of hands, with the results telephoned through before they are totted up.
Points mean victories
Each state holds a primary or a caucus to decide who they want as the candidates.
Depending on the size of the state the vote is worth more. So, because California has a larger population it's worth much more than, say, Wyoming, which is small.
Eurovision-style, the totals from each state are added up.
The candidates from each party who get the majority of votes go on to become the presidential candidate for each side.
Who is the battle between?
On the Democrat side it is Hillary Clinton and Barack Obama.
For the Republicans the candidates are John McCain and Mike Huckabee.