Re-elected incumbents and candidates-elect get to celebrate their victories through inaugural activities and swearing-in ceremonies. Banquets, balls, parades, and speeches are all characteristic of inaugural ceremonies, which can last multiple days.
However, the most important part of the celebration is the swearing-in. All candidates have to take an oath of office, in which they promise to discharge the duties of their office. From this moment, they are public servants, entrusted by all of us to "faithfully execute the office [to which they are elected]... to the best of [their] ability."
After all the excitement and ceremony, the one election cycle comes to a close. And another one begins...