Politics of the United States takes place in a framework of a Presidential republic, whereby the President of the United States is head of State, head of government, and of a two-party legislative and electoral system.
The executive branch is headed by a President and is independent of the legislature. Legislative power is vested in the two chambers of Congress, the Senate and the House of Representatives. Judicial power is exercised by the judicial branch (or judiciary), comprised of the Supreme Court and lower federal courts.
And the road to the White House is quite long, complicated and expensive.
Bare beginnings
In the early stages, any politician with ambition to become President usually forms an exploratory committee to study the present scenario of the State and raise money, sometimes up to two years before the election.
They then formally declare their candidacy and campaign in key States.
Campaigning
The candidates campaign in two different ways. That is, through primaries and caucuses. The primary season begins in the January before the election and lasts until about June. This is where candidates fight within the two main parties, Republican and Democratic, for their party's nomination. Some States use a caucus - a local meeting system. The results of these meetings are combined on a State-wide basis to determine a State’s party nominee. The winning candidate then picks a running-mate, sometimes from among the defeated rivals.
The final countdown
This is when the candidates fully square up against each other. There is massive spending on advertising, and a major flurry of State-by-State campaigning. Much attention is paid to the televised debates between the candidates. This can, but does not necessarily involve any independent candidate.
In the final weeks, the contenders typically concentrate their attention on big so-called "swing States", where the outcome is uncertain.
The election
American Presidential elections are always held on the first Tuesday after the first Monday in November.
Voters do not, technically, participate in a direct election of the President. They choose ‘electors’, who are pledged to one or another candidate. This is known as the Electoral College.
Each State has a certain number of electors to the college, based on the size of its population.
In almost every State, the winner of the popular vote gets all the Electoral College votes in that State. Because of this system, a candidate can take the White House even without winning the popular vote.