"It is with deep sorrow that Her Majesty The Queen announces the death of her beloved husband, His Royal Highness Prince Philip, Duke of Edinburgh," Buckingham Palace announced in a statement.
"His Royal Highness passed away peacefully this morning at Windsor Castle. The Royal Family join with people around the world in mourning his loss."
After any royal family member dies there is a protocol to follow, with each senior member given their own codename, which is always a bridge, to describe their respective procedure.
For Prince Philip, the codename is Operation Forth Bridge. Here's everything you need to know about what the operation entails, from funeral plans to where he'll be laid to rest.
What happens after Prince Philip dies?
The first part of Operation Forth Bridge is to announce Prince Philip's death.
The news was given to the Press Association and BBC first, while Buckingham Palace also made an announcement on their social media accounts. Next, Prime Minister Boris Johnson delivered a statement outside 10 Downing St.
Now, the UK enters a period of national mourning.
The UK government has announced that until the day after Prince Philip's funeral, union and national flags will fly at half-mast on all government and royal buildings. That's all except for the Royal Standard, which represents the Sovereign and the United Kingdom; that will be flown at full-mast when the Queen is present.