Markle won't be following the American tradition of asking 14 of her closest friends to walk her down the aisle in matching empire waist dresses. Instead, it's tradition to have a legion of little girls who are related to the royal family be the bridesmaids, between the ages of 10 to 12.

For her wedding, Kate Middleton used three-year-old Grace van Cutsem, who was Prince William's goddaughter, three-year-old Eliza Lopes, who was Camilla's granddaughter, and seven-year-old Lady Louise Windsor and eight-year-old Margarita Armstrong-Jones, who were both Prince William's cousins. Middleton did break with tradition, however, when she made her sister Pippa the oldest maid-of-honor in recent history, at the ripe old age of 27.

Even if Markle and Middleton became super close these past couple of months and Markle wanted her to be her Matron of Honor, she wouldn't be able to ask. There's a rule that a person of higher rank can't trail behind a commoner, as was evidenced when Pippa couldn't ask her own sister to be her Matron of Honor in her society wedding in 2017.

"It's unbecoming for a member of the royal family to walk behind a commoner — which, as painful as that sounds and despite being directly related to Catherine, is what Pippa is," shared William Hanson, a British etiquette expert, to Cosmopolitan.

Have you noticed all the playful, elaborate, and almost architectural hats English women tend to wear to royal weddings? It turns out that those are mandatory. Ladies have to dress appropriately to church, where they must cover their shoulders, wear appropriately-length dresses, and also cover their hair.

Back in the 1800s everyone wore hats because it was a sign of modesty and respect, and then around the '60s the trend began to peter off — but not during major royal engagements, like a wedding ceremony.

But why are the hats so elaborate? The reasoning is two-fold: The more festive they look, the happier you look for the couple getting married. And the more elaborate the design, the more expensive the accessory is, which shows your standing in society. The higher your rank, usually the quirkier your hat will be.

Nicknamed the "herb of love," it's a royal tradition to include myrtle in the bridal bouquet, which was started in the 1800s when Queen Victoria married Prince Albert. After their wedding she planted the myrtle in their garden, and each royal bride since has carried a sprig from that bush in her own bouquet — everyone from Queen Elizabeth, to Princess Diana, to Kate Middleton.

Starting with Prince Albert's wedding where he married Queen Victoria in 1840, the Prince stood at the alter in his full military garb. In the years since, royal grooms have come to the chapel wearing their military uniforms, including Prince Philip, who wore his naval commander uniform, Prince Charles, who wore his naval commander garb, and Prince William, who wore his Irish Guard Colonel uniform.

Seeing how Prince Harry has completed two tours in Afghanistan and has been in the army for 10 years with the rank of Captain, he will most probably be showing up in his uniform, too.

A new-ish tradition, royal wedding rings have been made out of Welsh gold since 1923, when George VI and Elizabeth Bowes Lyon walked down the aisle together. (They are the parents of Queen Elizabeth.)

For their nuptials the couple was gifted with a nugget of gold from a mine in North Wales, and the family has used the gold to make every wedding band since— from the Queen Mother’s ring, to Queen Elizabeth's, to Princess Margaret's, to Princess Diana's, and Kate Middleton's.

While not an official rule, it's customary for the royal bride to choose a British designer in order to celebrate local talent, as well as boost the country's economy by marketing their goods throughout the important day. The tradition started with Queen Victoria in 1840, when she broke with tradition and wore a white dress (she was one of the first to do it!) in order to better showcase the Honiton lace on the gown. The artisanal lace counties were dying off thanks to the Industrial Revolution, and the Queen knew that if she showcased their craftsmanship on her wedding day, it would be written about for months — which it had been.

Queen Elizabeth followed suit by asking British designer Norman Hartnell to design her dress, Princess Diana enlisted Elizabeth Emanuel, and Middleton used Alexander McQueen.

You won't see Markle wearing a bold manicure on her wedding day — in fact, the only time she will be able to rock a bright nail polish color will be when she's spending time at home and not engaging in royal duties. Only natural-looking nails are allowed at official royal events, including giant wedding celebrations!

This seems like an oddly specific rule, and it's around for no other reason than Queen Elizabeth simply doesn't like wedges. She doesn't like the look of them, and so she doesn't want to see 'em. Which is fair enough.

"The Queen isn't a fan of wedged shoes. She really doesn't like them and it's well known among the women in the family," a royal source told Vanity Fair.

So you can probably expect that there won't be a cork wedge in sight at St George's Chapel.

Another fast and hard rule of the queen's is to always have tights on, so it's a fair assumption that all the women in attendance at the chapel and reception will have sheer pantyhose on, at the very least. When the queen puts down the rules of etiquette, you better follow them.

From playful hats, to myrtle-heavy bouquets, to adorable 10-year-old bridesmaids, this is going to be a fun wedding to watch!