The ceremony after a person takes office is called an "inauguration."
A person is a 'lame duck' if he or she has lost the election (or did not run for a new term) during the time between the election and the swearing in of new office holders.
Inauguaration
The date is January 20 in the year after the November election.
That's Inauguration Day, when the winner of the election officially takes office.
The ceremony is called the inauguration.
The inauguration ceremony of a newly elected president takes place on January 20 of the year following the election.
inauguration
inauguration
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The Chief Justice of the US does nothing special in the election process. By tradition, he administers the presidential oath when the president takes office.
inauguration
He takes the oath of office on 20 January, following the election in November.