President-elect Donald Trump's Twitter-issued command to folks celebrating his swearing-in this week: "Have fun!"

One way citizens might answer his call to action is by attending an inaugural ball, one of the fancy formal dos happening on the eve and night of the inauguration. Here's a guide:

What makes a ball 'official'?
Of the dozens of balls and parties happening in Washington, only official balls - those sponsored by the Presidential Inaugural Committee (PIC) - are guaranteed destinations for the newly sworn-in President and First Lady.

Since it opened in 2003, the Washington Convention Centre has become the site of the official parties - President Barack Obama held six of his 10 balls there in 2009 and all three of his 2013 soirees. This year, the PIC is sponsoring two balls there and a third at the Building Museum for veterans, service members and first responders. Trump's team has been given US$90 million ($125m) to spend on the inaugural.


There are dozens of unofficial balls, typically held in hotel ballrooms and often sponsored by state societies. Texans will be partying at the Black Tie and Boots ball at the Gaylord hotel, where fancy footwear and Stetsons are de rigueur and brisket is on the menu.

Who gets tickets?
For the official balls, tickets are distributed by the PIC, going mostly to donors and supporters. There's an open market for the unofficial balls, with tickets ranging widely in price: US$75 will get you into the Asian Pacific American Presidential Inaugural Gala at the Mayflower, or you could pay US$10,000 for a VIP table of 10 at the Deplorables ball at the Ronald Reagan Building.

What's the dress code?
It's dress to impress. Inaugural balls are still black-tie affairs. The First Lady sets the tone, with a gown so significant it will likely wind up on display at the National Museum of American History.

While fashion watchers are waiting this year to see which designer will dress Melania Trump, the selection of a dress for the high-profile affair has always been fraught. One example? Mindful of the economy, Rosalynn Carter re-wore an off-the-rack gown to her husband's 1977 inauguration but got blasted by critics.

What about the dance?
It's a bit like a wedding, where the President and First Lady take to the dance floor for some awkward shuffling and G-rated PDA. Some Presidents seem to enjoy the ritual (Ronald Reagan had some pretty smooth moves), while others clearly don't (George W. Bush hammily checked his watch seconds into one of his 2001 inaugural dances). The music varies - often, it's a slow jazzy number, and in 2009 Beyonce famously serenaded the Obamas.

But pop stars aren't always the only entertainers: Bill Clinton hopped onstage at one of his 1993 inaugural balls and played saxophone with the band.

So these are pretty swanky affairs, right?
Not exactly. Ball veterans often use the phrase "cattle call". For one, you're not exactly partying with the first couple, who typically ditch the room after one song and a quick wave. And good luck finding a drink.