There Are Very Specific Rules When It Comes to Dressing For the Royal Calendar

There is a VERY extensive list of rules, but basically it's:

• Women: Formal daywear, which means dresses and skirts of "modest length" (just above the knee or longer), and straps on dresses should be at least an inch wide. Fascinators are no longer allowed as headpieces need to have a base of four inches or more. No off-the-shoulder or halter tops, and ladies are advised to wear wedges over stilettos so they do not sink heel-first into the ground.
• Men: Black or gray morning dress, which means a tailcoat and waistcoat with matching trousers, along with a dress shirt and tie. No cravats. Black or gray top hat and black shoes.

• The Queen/Knights and Ladies of the Garter: Dark blue velvet cloaks pinned with the Garter Star and velvet hats decorated with ostrich and heron feathers.
• Women: Daytime formal plus hat.
• Men: Morning dress — tails and waistcoat — but no top hat.

• Women: Dresses, skirts, or tailored trousers. No flip-flops.
• Men: Collared shirts, trousers, and jackets. No shorts no matter how hot it is.

• Women: Just because there are horses involved, there's no posh dress code behind the scenes. It's your basic "running errands" attire — jeans, tees, and flats.
• Men: Although Prince Charles maintains an element of formality, the younger men stick with jeans or shorts with a t-shirt or polo shirt. As long as nothing is torn or stained, the more casual the better.

• Women: The black-tie dress code calls for a floor-length gown.
• Men: Black tie means bow tie, dress shirt, and tuxedo.

• Women: All in black. Smart coat and hat. Always pinned with a poppy.
• Men: Military uniforms pinned with a poppy. William wears his RAF flight lieutenant's uniform and Harry his captain's uniform of the Blues and Royals.

• Women: It's daytime formal with a hat for the ladies. Cold weather usually means a coat.
• Men: Suit and tie.

• Women: There is no designated dress code, but women tend to go for daytime formal with a hat.
• Men: Suit and tie.

• Kate: Daytime formal with a hat. In a nod to the occasion, Kate usually wears green, but she did once wear brown.
• William: His colonel of the Irish Guards uniform.

• Women: Formal daywear with a hat. Fascinators are OK, but they have to be "substantial."
• Men: Morning suit with top hat.