Britain's Queen Elizabeth rides her horse in the grounds of Windsor Castle, three days after the death of her mother, in this April 2, 2002 file photo. [Photo/Agencies]

Queen Elizabeth famously has two birthdays: her actual birthday on April 21 and her official birthday which takes place in June.

Celebrations were not at its heart on her actual birthday and the Queen mainly demonstrated her commitment to duty with a routine engagement in Windsor. The Queen, accompanied by her husband, visited the Royal Mail Windsor delivery office on Wednesday as a token to show her appreciation to the Postal Service's 500-year dedication to the country.

She's famous for her love of horses and dogs, her dedication to the Commonwealth and international affairs.

Her 90th birthday celebration takes place from April to May then on to June. From May 12 to 15, 900 horses and more than 1,500 riders and performers will tell the story of the Queen's remarkable life at 90-minute long extravaganza in the private grounds of Windsor Castle.

The Queen's official birthday is always marked with a traditional parade known as the Trooping of the Colour, which sees the famous bearskin-hatted Guards with their red ceremonial jackets march behind the Queen's personal standard, or flag, accompanied by the mounted Household Cavalry and the other armed services; the Royal family will then appear on the balcony of the palace to watch a fly-past by the Royal Air Force. The whole celebration will be wrapped up with a huge street party on 12th June where 10,000 guests will enjoy a picnic and street performances.

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