U.S. presidential elections occur every four years, where citizens vote to choose their president. The process begins with primary elections, where political parties select their candidates. The two main parties are the Democratic Party and the Republican Party. In November, the general election takes place, and voters cast their ballots for their preferred candidate. The winner is determined by the Electoral College, which allocates votes based on each state's population. The candidate who receives a majority of the electoral votes becomes the president, officially taking office in January.