The inauguration of the President of the United States takes place during the commencement of a new term of a President of the United States, which is every four years on January 20. Prior to the Twentieth Amendment, the date was March 4. The day a presidential inauguration occurs is known as "Inauguration Day".

The only inauguration element mandated by the United States Constitution is that the President make an oath or affirmation before that person can "enter on the Execution" of the office of the presidency. However, over the years, various traditions have arisen that have expanded the inauguration from a simple oath-taking ceremony to a day-long event, including parades, speeches, and balls.