This year's Commonwealth Day falls on Monday, March 14.
It's an annual celebration of the Commonwealth of Nations, which is held on the second Monday of March every year and will be marked by a service that is broadcast live on television.
The Queen, who is Head of the Commonwealth, will not be in attendance and will be represented by The Prince of Wales at the annual Commonwealth Service at Westminster Abbey instead.
Read more: The four-day bank holiday weekend we're all getting soon for Queen's Platinum Jubilee
On Friday, a Buckingham Palace spokesman explained: "After discussing the arrangements with the royal household, the Queen has asked the Prince of Wales to represent Her Majesty at the Commonwealth service at Westminster Abbey on Monday.
"The Queen will continue with other planned engagements, including in-person audiences, in the week ahead."
Also attending the service will be The Duchess of Cornwall, The Duke and Duchess of Cambridge, and Princess Alexandra.
Here's everything you need to know.
When will the Commonwealth service start?
Those who want to watch the ceremony can do so as BBC One will broadcast the Service of Celebration from Westminister Abbey from 2pm.
The Service of Celebration itself is taking place between 2.40pm - 3.45pm and will be the first in-person gathering of the Commonwealth since the start of the pandemic and will reflect Her Majesty’s Platinum Jubilee Year. You can read more on this here.
The ceremony will include an address by the former Archbishop Lord Sentamu and performances from Emeli Sandé and Mica Paris.
If you miss the live broadcast you can watch it on catch up on the BBC iPlayer.
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