Celebration of the Queen's Birthday in a Ceremony Trooping the Colour.

Today the Duke and Duchess of Cambridge, along the entire royal family, is observing the official celebration of the Queen's birthday in a ceremony known as Trooping the Colour. Although The Queen was born on April 21st, it has long been the tradition to celebrate the Sovereign's birthday publicly on a summer day, when good weather is more likely.

Trooping the Colour is carried out by fully trained and operational troops from the Household Division (Foot Guards and Household Cavalry) on Horse Guards Parade in Whitehall, watched by members of the royal family, invited guests and members of the public. The military ceremony dates back to the early eighteenth century or earlier, when the colours (flags) of the battalion were carried (or 'trooped') down the ranks so that they could be seen and recognized by the soldiers.

The annual Trooping the Colour ceremony.

The annual Trooping the Colour ceremony.

The annual Trooping the Colour ceremony.

During the ceremony, The Queen is greeted by a royal salute and carries out an inspection of the troops. After the massed bands have performed a musical 'troop', the escorted Regimental Colour is carried down the ranks. The Foot Guards and the Household Cavalry then march past Her Majesty, and The King's Troop, Royal Horse Artillery, rank past. 

                The Queen, accompanied by the her cousin, the Duke of Kent, in Prince Philip's absence, 

                                                              reviewing military personnel. 

The Queen and the Duke of Kent reviewing military personnel during the annual Trooping of the Colour ceremony.

The Queen rides in a carriage back to Buckingham Palace at the head of her Guards, before taking the salute at the Palace from a dais. The troops then return to barracks. Her Majesty then joins other members of the royal family on the palace balcony for a fly-past by the Royal Air Force.
 

The RAF Red Arrows perform a flypast over Buckingham Palace following the Trooping of Colour ceremony.

The royal family watching the fly over on the balcony at Buckingham Palace.

Prince Harry and the Duke and Duchess of Cambrige on the balcony at Buckingham Palace during the annual Trooping the Colour ceremony.

Prince Harry, Camilla, Duchess of Cornwall and Catherine, Duchess of Cambridge share a laugh on the balcony at Buckingham Palace during the annual Trooping the Colour ceremony.

Sophie, Countess of Wessex, Lady Louise Windsor, Sir Timothy Laurence, Prince Harry, Camilla, Duchess of Cornwall, Catherine, Duchess of Cambridge, Princess Eugenie, Prince Andrew, Duke of York and Princes Beatrice standing on the balcony at Buckingham Palace.

The Queen has attended Trooping the Colour every year of her reign, except in 1955 when a national rail strike cancelled the event.

— 2013 Trooping the Colour

Prince Harry, Camilla, Duchess of Cornwall and Catherine, Duchess of Cambridge, arriving for the annual Trooping the Colour ceremony at Buckingham Palace.

Prince Harry, Camilla, Duchess of Cornwall and Catherine, Duchess of Cambridge, arriving for the annual Trooping the Colour ceremony at Buckingham Palace.

The Queen arriving for the annual Trooping the Colour ceremony.

The Queen, accompanied by the her cousin, the Duke of Kent, in Prince Philip's absence, arriving for the annual Trooping of the Colour ceremony.

Camilla, Duchess of Cornwall and Catherine, Duchess of Cambridge, arriving for the annual Trooping the Colour ceremony at Buckingham Palace.

Prince William participating in the annual Trooping of Colour ceremony.

Prince William participating in the annual Trooping of Colour ceremony.

Prince Charles and Prince William participating in the annual Trooping the Colour ceremony at Buckingham Palace.

Prince Charles, Prince of Wales and Princess Anne, Princess Royal on horseback during the annual Trooping the Colour Ceremony at Buckingham Palace.

The Earl and Countess of Wessex arriving for the annual Trooping the Colour ceremony.

Princess Beatrice (left) and Princess Eugenie (right) arriving for the annual Trooping the Colour ceremony.