Elizabeth at 90: The highs and lows of the Queen's reign

Catherine, Duchess of Cambridge laughs as Queen Elizabeth gestures during a visit to Vernon Park in Nottingham, England, in this June 13, 2012 file photo.

Phil Noble/Reuters

LONDON -- Queen Elizabeth II marks her 90th birthday on Thursday as Britons and many throughout the world celebrate her long and dignified reign. She will celebrate again in June with national events to mark her official birthday.
Here are answers to some questions about the queen's extraordinary life and times:
Why two birthdays a year? Isn't one enough?

It may seem excessive, but the British monarch celebrates his or her birthday twice a year, once on the actual day (for Elizabeth, April 21), and once in early June, when the event can be marked with the gala Trooping the Color parade in central London. The June date is chosen in part because the famously fickle British weather just might produce a few sunny hours at that time of year. And the Buckingham Gardens are gloriously in bloom.

How did Elizabeth spend her last day as an 89-year-old?

The monarch on Wednesday toured her local Windsor postal depot, which was renamed in her honor. "I have it on good authority that your own postmen and women will be especially busy with tomorrow's mailbag," Royal Mail Group chief executive Moya Greene said as she thanked the queen for coming to mark the 500th anniversary of the Royal Mail. A crowd waved the nation's flag in the sparkling sunshine as two Royal Mail choirs and another one from Bristol sang "Happy Birthday."

When did she become Queen?

Elizabeth's life was changed forever in 1936 when her uncle, King Edward VIII, abdicated so he could marry his divorced lover Wallis Simpson. This made her father the king and Elizabeth heir to the throne. King George VI's health failed, however, and he was too ill for a planned tour of the Commonwealth in 1952, so he sent Elizabeth and her husband, Prince Philip, in his place. They were staying in a remote part of Kenya on Feb. 6, 1952, when she was told that the king had died. She automatically became queen upon her father's death, although the official coronation did not take place for more than a year.

How did Elizabeth weather World War II?

Elizabeth was a young princess during World War II, and her father King George VI was concerned for her safety as London came under the repeated German bombing raids known as The Blitz. She and her sister Princess Margaret were moved to Windsor Castle, 25 miles (40 kilometers) west of London for security reasons. She later persuaded her parents to let her serve in the Auxiliary Transport Service, where she learned how to drive and repair ambulances and trucks as part of the war effort. She was assigned number 230873 while in the service.

Has the Queen ever complained in public?

No, that's just not done. The closest Elizabeth has come to exhibiting human frailty to her subjects was in 1992, when she made a rare admission that her life, so picture perfect on the outside, was marred by the marital woes of three of her four children. She didn't complain in English, however, looking to Latin to proclaim it had been something of an "annus horribilus" -- a horrible year that included a disastrous fire at her beloved Windsor Castle.

What was the low point of her monarchy?

This would undoubtedly be the stormy days that followed Princess Diana's sudden death in a car crash in August 1997. The princess was tremendously popular, and many held the royal family responsible for her unpleasant divorce from Prince Charles. The queen was castigated in the press for not returning to London immediately after Diana's death and for not flying the royal standard atop the palace at half-staff as a sign of respect. Thousands of mourners placed flowers at the gates of Kensington Palace, Diana's residence, and many complained the queen was insensitive and out of touch.

Who was her favorite prime minister?

You'd have to ask her. And she won't tell.

Does the Queen plan to retire?

The strong-willed and able-bodied queen has given no indication she plans to leave the throne, and has described her unique position as a "job for life." Her own mother lived to be 101, and was generally in fine fettle in her final years. Still, it is possible Elizabeth would step down if she developed severe problems that made it impossible for her to carry out her role.

Prince Charles is already 67. Could the Queen arrange things so grandson Prince William would succeed her?

No. This is a constitutional monarchy, with rules of succession.