Every four years citizens of the United States go to the polls to elect a President and Vice President. People who want to run for the President belong to political parties that have different ideas about how a government should work. People with similar ideas are members of the same party and compete for delegates who will represent their views at the upcoming conventions to select a candidate. The conventions will then decide the final presidential nominee for the party. The candidates will campaign throughout the country, holding rallies and taking part in debates to explain their plans and vision for society.
With the exception of Maine and Nebraska most states have a winner-takes-all system so that whichever candidate gets the majority of votes in a state wins all of the electors there. This makes it very important for the candidates to spend exponentially more time and money in a small number of swing states that could go either way.
The presidential race begins with candidates announcing their intentions to run early in the year before Election Day. This is a legal requirement for those who want to receive campaign contributions and to make political expenditures. Some candidates form exploratory committees even earlier to see if they can raise the funds and support necessary to run.
In the 2024 election Trump easily won the Republican Iowa caucuses and went on to win most of the other Republican primaries. This allowed him to accumulate the most delegates and officially become the Republican candidate. Biden did not do as well in the debates with Trump and, under pressure from prominent Democrats who feared losing the race, he dropped out of the race.