It's the most exclusive party on the calendar.
Millions of people around the world will watch on TV as Meghan Markle and Prince Harry say their vows inside St George's Chapel on Saturday.
A very carefully-selected 2640 members of the community — think charity workers and Royal Households staff — will be given access to the palace grounds for the ceremony.
Just 600 of the couple's friends and family have been invited inside the chapel, and to the formal reception which will follow.
And of that group, only 200 members of their elite inner circle get to go to the real event: the afterparty.
Read more: • Everything you need to know about the Royal Wedding
That's the hottest ticket in town, and the one part of the big day that will remain shrouded in mystery. Barely any details are known about Prince William and Kate Middleton's own post-wedding "private reception", seven years on — and those lucky enough to make the guest list know to keep their lips tightly sealed.
Even if they didn't — all guests received some "critical guidance" along with their invitations, according to the Mail on Sunday.
Critically, it is said to have informed them that all guests will have to hand over their mobile phones and cameras beforehand.
It's the only part of the day where Meghan and Harry will feel comfortable enough to share candid stories about their relationship during their speeches. It's also where best man William will absolutely drop some hilarious shade on Harry, just like his younger brother reportedly did to him back in 2011.
It's also highly likely there'll be heartfelt tributes to the late Princess Diana from both her sons, just as there reportedly was at William's reception.
However, while the event is being closely guarded, there are some details we know:
The private party is being held at Frogmore House, which is just a few minutes' drive away from the earlier formal reception at St George's Hall in Windsor Castle.
Frogmore is an official royal residence and has been in the family for a long time. It was originally bought by George III in 1792 as a gift for his wife Queen Charlotte. It's famous for its beautiful gardens, with thousands of trees and the royal Mausoleum where Queen Victoria and Prince Albert are buried.
Of course, it also holds special significance for Harry and Meghan. Back in December, they chose it as the location for their official engagement photo shoot.
Just like the event they're throwing within its walls, Frogmore House is an incredibly private place. It's hard to get photos from inside the property as it's rarely open to the public — just a few days a year.
In March, Kensington Palace announced that it would be the venue of the reception, and that the event would be hosted by Prince Charles, who also threw William and Kate's post-wedding bash at Buckingham Palace.
"Later that evening, around 200 guests are being invited to the reception at Frogmore House given by The Prince of Wales," read the statement.
The guest list for the exclusive party has been kept predictably under wraps, but we do know of a few notable inclusions and exclusions.
Obviously, all the key players in the royal family are invited. The Queen, Prince Philip, Prince Charles and Camilla, Prince William, Kate Middleton and Princess' Beatrice and Eugenie will all be there, as will Meghan's mother, Doria Ragland.
Members of the cast of Suits are also invited — including Gabriel Macht and his wife Jacinda Barrett — along with Meghan's closest girlfriends, actress Priyanka Chopra, designer Misha Nonoo, stylist Jessica Mulroney and British reality TV star Millie Mackintosh.
While Prince Andrew's former wife Sarah Ferguson (or 'Fergie' as we all know her) did score an invite to the ceremony, she's reportedly "very unhappy" at being left off the guest list for the private function.
Chelsy Davy, Prince Harry's former on-off girlfriend of seven years, has reportedly also been snubbed from the event.
Despite the pair remaining good friends following their 2011 split, Davy was surprised to discover she was only invited to the ceremony and formal reception, according to the Mail Online.
Another surprise no-show is Pippa Middleton, Harry's sister-in-law who, according to media reports, is not invited to the wedding, despite the fact both the Prince and then-girlfriend Meghan attended her wedding reception last year.
According to The Mirror, the Frogmore party will be Tiki-themed, as an homage to one of Harry's favourite nightclubs, Mahiki.
It's understood there will be a steel band and drinks including "apache shooters" (something involving Kahlua, Midori and Baileys Irish Cream) and vodka luges carved from ice.
Meanwhile, it's been reported this week that Elton John is set to perform.
According to TMZ, the Tiny Dancer singer will belt out some tunes, but it's not yet known whether it will be at the church ceremony or one of the later receptions.
Elton has had a close association with the royal family for decades and worked with Harry's mother Princess Diana on AIDS research.
Elton also performed Candle in the Wind at Diana's funeral in 1997.
Speculation had already been rife that Elton was set to appear either as a guest or performer at Harry and Meghan's wedding after the singer cancelled his scheduled concerts in Las Vegas this weekend.
Meanwhile, it was confirmed on Wednesday that the Spice Girls will not perform at the wedding, despite Mel B telling a US chat show they would reunite and sing at the nuptials.
"Only Victoria, Emma and Geri were invited, so clearly, the Spice Girls were never going to perform," a source told Page Six.
Mel C was not invited, and neither was Mel B, who is at her home in Los Angeles.
Either way, given that British pop star Ellie Goulding performed at William and Kate's reception, we're expecting big things in the entertainment space for Harry and Meghan's.
Proving that they're the ultimate trendy couple, Harry and Meghan have decided to have food trucks to tide over hungry revellers.
According to an "exclusive reveal" by the Sunday Express, the reception will end with late-night snacks, including ice-cream vans.
It's not that surprising, considering Harry convinced his brother to have food trucks full of bacon and sausage sandwiches at his own wedding back in 2011. William and Kate also reportedly had an ice-cream truck at their wedding as a dessert alternative.
Why eight hours a night is the sweet spot for sleep.