The UK sovereign has received a myriad of congratulations, from members of the royal family, to people from around the globe alike.
The Duke and Duchess of Sussex wished their "Granny" a wonderful day, posting a series of the queen's pictures from various periods of her life.
Meanwhile, the Duke and Duchess of Cambridge also did not forget to congratulate the monarch on her birthday.
Ordinary Internet users also joined in the chorus of warm congratulations to the monarch.
Elizabeth II was born in London as the first child of the Duke and Duchess of York, later King George VI and Queen Elizabeth. She ascended to the throne on 6 February 1952, which makes her the longest-reigning monarch the UK has ever known, being in on the throne for 67 years and 72 days.