Final answer:
The biggest and fanciest party at the White House is called the inaugural party and it takes place after a president is sworn into office.
Step-by-step explanation:
The biggest and fanciest party at the White House is called the inaugural party. It takes place after a president is sworn into office and is a tradition that dates back to Andrew Jackson's presidency in 1829.
During the inaugural party, thousands of people line Pennsylvania Avenue and the president opens the White House to the public for a reception. The party often involves festivities, such as music, dancing, and refreshments.
This celebration is significant because it symbolizes the peaceful transfer of power and represents the support and well-wishes of the American people for the new president.