Royal Ascot is made up of five days of horse racing, star-spotting and elegant style.
Attended by the royals, this year including newlywed Meghan Markle, Ascot is considered the most sartorially superior event in the racing calendar thanks to its strict dress code.
So, whether you're in the Windsor or Royal Enclosure, here's this year's Ascot style guide, to help you avoid any awkward 'you can't come in here' moments at the door.
Dresses and skirts must be knee length
No matter which enclosure you're in, to be safe, make sure your ensemble falls below the knee, or just above.
This is a must for the majority of the enclosures, but the more casual Windsor Enclosure does state: "While no formal dress code applies here, we encourage racegoers to dress for the occasion". In plain speak, that's smart attire and hats are strongly encouraged.
It's also worth stating that fancy dress, replica shirts, novelty and branded clothing are also not allowed.
Jumpsuits are a go-go
Last year Ascot made the surprising decision to add jumpsuits to the bill for the first time.
"The inclusion of jumpsuits as part of the Royal Enclosure dress code recognises our customers’ fashion-forward taste and reflects our awareness of seasonal trends" said Julie Slot, Commercial Director at Ascot.
However, you must make sure that the design is full-length and, naturally, no midriff should be on show.
Suits are also allowed (yay!)
"Trouser suits are welcome. They should be of full length to the ankle and of matching material and colour."
Do not wear strapless styles
Yep, all those trendy off-the-shoulder styles are a no-no.
Ascot has strict policies about straps, and whether it's a top, jumpsuit or dress, it cannot be a strapless silhouette.
Not only that, but halter neck, spaghetti straps and sheer straps are also not permitted.
Fascinators are NOT allowed
This year Ascot has stepped up their hat game, meaning that most fascinators will no longer be allowed in the Royal Enclosure.
The rules state that those in the top tiered enclosure must wear a headpiece "which has a solid base of 4 inches (10cm) or more".
However, if you are in the Village, Queen Anne or Windsor enclosure, there is no stipulation on headgear size, however, whatever is on your head still has to be worn at all times.
Colour is not allowed
You can wear colour in abundance in the Windsor and Queen enclosure, but, it should be noted that "gentlemen are required to wear a suit with jacket and trousers of the same colour and pattern with a shirt and tie."
If you're in the Royal Enclosure it's a colour-free zone as only grey or black morning suits and top hats are allowed.
Don't want to splash out on an ensemble? We recommend hiring a morning suit or top hat from Oliver Brown in Chelsea.
Socks are a must
As the rules at Royal Ascot get stricter year-on-year, a rather unusual addition has been made for 2018 - all men must wear socks.
Yes, you heard correctly: no socks, no entry.
Regardless of whether you're in the Royal Enclosure or not, you can be refused entry if you turn up with bare feet inside your shoes.
All is not lost, though; Ascot have a selection on socks on-hand to lend if needs be.
Cravats are not permitted
Men are also expected to wear a tie at all times.
A tie being the only accessory (other than a top hat) that gentlemen are allowed, with cravats and bow ties both a no-no.