Anyone who is an American citizen,

Anyone who is an American citizen, at least 18 years of age, and is registered to vote may vote. Each state has the right to determine registration procedures. A number of civic groups, such as the League of Women Voters, are actively trying to get more people involved in the electoral process and have drives to register as many people as possible. Voter registration and voting among minorities has dramatically increased during the last twenty years, especially as a result of the Civil Rights Movement.
There is some concern, however, about the number of citizens who could vote in national elections but do not. In the national election of 1984, for instance, only 53.3 per cent of all those who have voted actually did. But then, Americans who want to vote must register, that is put down their names in register before the actual elections take place. There are 50 different registration laws in the US - one set for each state. In the South, voters often have to register not only locally but also at the county seat. In European countries, on the other hand, "permanent registration" of voters is most common. Of those voters in the United States who did register in the 1984 presidential elections, 73 per cent cast their ballots.
Another important factor is that there are many more elections in the US at the state and local levels than there are in most countries. If the number of those who vote in these elections (deciding, for example, if they should pay more taxes so a new main street bridge can be built) were included, the percentage in fact would not be that much different from other countries.
Certainly, Americans are much more interested in local politics than in those at the federal level. Many of the most important decisions, such as those concerning education, housing, taxes, and so on, are made close to home, in the state or county.
The national presidential elections really consist of two separate campaigns: one is for the nomination of candidates at national party conventions. The other is to win the actual election. The nominating race is a competition between members of the same party. They run in a succession of state primaries and caucuses (which take place between March and June). They hope to gain a majority of delegate votes for their national party conventions (in July or August). The party convention then votes to select the party's official candidate for the presidency. Then follow several months of presidential campaigns by the candidates.
In November of the election year (years divisible by four, e.g. 1988, 1992, 1996, etc.), the voters across the nation go to the polls. If the majority of the popular votes in a state go to the Presidential (and vice-presidential) candidate of one party, then that person is supposed to get all of that state's "electoral votes." These electoral votes are equal to the number of Senators and Representatives each state has in Congress. The candidate with the largest number of these electoral votes wins the election. Each state's electoral votes are formally reported by the "Electoral College." In January of the following year, in a joint session of Congress, the new President and Vice-President are officially announced.