© Getty Images

Celebs are briefed before meeting a royal -

Yes, they'll receive instructions on royal protocol beforehand, so they know what to expect and how to behave accordingly. 

© Getty Images

Royal aides will know stuff about a specific celebrity -

And they'll brief it to the member of the royal family prior to their meeting. 

© Getty Images

Aides are present -

Personal aides will liaise with celebs in advance and will likely be present when they meet.

© Getty Images

Celebs have to RSVP twice for Buckingham Palace invites -

Usually celebs have to do so via email and then by responding to a formal invitation by mail. 

© Getty Images

Celebs must arrive early when meeting the Queen or the King -

The Royal is supposed to be the last person to arrive at any given event, so celebs must be there beforehand, waiting for her. 

© Getty Images

Stand for the Queen and King -

Everyone must stand when the Queen or the King enters a room, regardless of your status. 

© Getty Images

Celebs only have to curtsy to the Queen or King -

All other members of the royal family don't require this formal greeting. 

© Getty Images

Celebs shouldn't touch a royal -

Well, this will depend on their level of intimacy, but the physical contact should always be initiated by the royal. 

© Getty Images

Don't speak until you're spoken to -

Classic royal protocol that everyone should follow, including celebs.

© Getty Images

Royals are not schoolmates -

And celebrities can't even address members of the royal family by their first name. 

© Getty Images

Celebs should not use nicknames -

Beyoncé referred to Meghan Markle as "my princess" at 'The Lion King' premiere.

© Getty Images

Handshake is the standard -

A simple handshake will suffice when meeting a royal, no matter how famous you are. 

© Getty Images

Follow the royal lead -

When it comes to formality, celebs are expected to follow the royal lead on it. 

© Getty Images

Try not to be a goof -

A good sense of humor is great, and the royals appreciate it, but it's best to keep the jokes to yourself. 

© Getty Images

It's normal to feel nervous -

Even big stars have to try hard to follow royal protocol without freaking out about meeting the Queen or King. 

© Getty Images

Security -

Celebs must be aware of security, and not to be tempted to crack a joke that might be perceived as threatening to the royal family. 

© Getty Images

Celebs don't have unlimited access -

Some Buckingham Palace rooms are off-limits, even for celebrities. 

© Getty Images

Eye contact is a must -

Everyone should make eye contact when speaking and being spoken to by the Queen, including celebs. It looks like Vogue's Anna Wintour breached royal protocol. 

© Getty Images

No dinner chit-chat -

Famous people who sit next to the Queen or the King for dinner should wait until they take the initiative and initiates conversation. And it goes without saying that impeccable table manners are a must. 

© Getty Images

Don't decline an invitation from the royals -

Helen Mirren did so once, due to her busy filming schedule, and the story ended up in the press. 

© Getty Images

Dress code for royal weddings -

Yes, celebs must also abide by the traditional dress code. This includes classic, formal attire and a hat for the ladies. 

© Getty Images

Don't wear bright colors -

The Queen is the one expected to shine, not you. In this case, it was Elton John, so bright and flashy was to be expected. 

© Getty Images

Celebs shouldn't ask for an autograph -

Though this is no longer as strict, the royal family is not supposed to give autographs, even if it's for a celeb. 

© Getty Images

Celebs shouldn't get a selfie -

Protocol is not as strict as it once was on this, but famous faces will likely have professional photographers or paparazzi capturing the moment anyway. 

© Getty Images

Don't leave before a royal -

What, you're a busy artist and need to be somewhere else? You still have to wait until the member of the royal family leaves or gives you permission to do so. 

© Getty Images

Don't turn your back on the Queen or King -

This is a no-no. Even for famous people. Don't do it. 

© Getty Images

BAFTAs -

The Prince and Princess of Wales are the patrons of the British Film Academy and are always the last to arrive. Everyone, including celebs, must give them a standing ovation when they enter a room.

© Getty Images

Plus-ones should stay further back -

Even famous plus-ones should stand behind the guest and should only speak when spoken to. 

© Getty Images

Even photographers have a dress code -

Yes, royal press correspondents have a dress code they must follow. 

Source: (Marie Claire)

See also: The royal family's secret travel rules

© Getty Images