The annual celebrations include Trooping the Colour, a march which takes place on Horse Guards Parade in London.
So, what is Trooping the Colour, when does it take place this year - and how can you watch at home? This is what you need to know.
What is ‘Trooping the Colour’?
Trooping the Colour is a military parade which takes place on the second Saturday in June each year. This year it will take place on 12 June 2021.
It usually attracts thousands of well-wishers to central London who line the Horse Guard parade grounds - situated just a short walk from Whitehall.
The celebrations have been used to mark the official birthday of the British Sovereign for over 260 years.
According to the Royal Household website, over 1400 parading soldiers, 200 horses and 400 musicians put on a display of great military precision and fanfare to celebrate the monarch.
The public would usually line the streets with British flags and other flag-dawning memorabilia, as the parade moves from Buckingham Palace and down The Mall to Horse Guards Parade, alongside Members of the Royal Family on horseback and in carriages.
The display closes with an RAF fly-past, watched by Members of the Royal Family from Buckingham Palace balcony.
The Queen previously attended the celebrations on horseback, inspecting the soldiers in their ceremonial uniform of red tunics and bearskin hats.
In recent years, she has attended by travelling in a carriage and been accompanied by the late HRH Duke of Edinburgh, Prince Philip.
Will it go ahead this year?
Despite an alleviation of many Covid restrictions, Buckingham Palace announced in March that, for the second year in a row, the event will not be made public and a scaled down affair would replace it.
The palace released a statement which read: "Following consultation with Government and other relevant parties it has been agreed that The Queen’s Official Birthday Parade, also known as Trooping the Colour, will not go ahead this year in its traditional form in central London. Options for an alternative Parade, in the quadrangle at Windsor Castle, are being considered."
The statement also confirmed that the annual Garter service, which usually takes place in June, "will not take place this year."
Instead, the queen and her cousin - the Duke of Kent - will attend a smaller version of the parade at Windsor Castle, where Prince Philip’s funeral was held on 17 April and where the queen has resided throughout the pandemic.
The parade will be led by the Foot Guards, who will be joined in the Quadrangle by The King’s Troop Royal Horse Artillery and the Household Cavalry Mounted Regiment.
They will fire a 41 gun royal salute from the East Lawn of the castle.
Will there be a flypast this year?
The usual RAF flypast will not take place at Buckingham Palace this year, as the event will be held at Windsor and other members of the royal family will not be in attendance.
It is not known whether there will be one at Windsor, NationalWorld has contacted the Queen’s press office for more information.
Will Trooping the Colour be on television?
For the thousands of royal fans who would like to take part in the day, BBC One will air ‘Trooping the Colour’ live at 10.15am on 12 June.
A highlights episode hosted by BBC correspondent Hugh Edwards will also be shown later on 12 June, on BBC One at 8pm.
You can watch both episodes later on BBC iPlayer.