The new date is Sep 8, 2022.
The crown was passed on to her heir, Charles, as part of the United Kingdom's constitutional monarchy system.
Buckingham Palace said in a statement that Charles is now king and that a coronation will take place later.
Prince William is the heir to the throne and he makes public appearances on behalf of the crown.
Second in line is William's 9-year-old son Prince George, who is an elementary school student beginning to take part in more engagements with his parents, having made his debut at the Wimbledon finals this year.
Prince Harry is the second son of Charles and Princess Diana.
Next in line are Harry's son and daughter with his American wife, Archie and Lillibet Mountbatten-Windsor, who all reside in California after Harry andMeghan stepped down as senior working royals.
The next in line for the throne is Elizabeth's second son, Prince Andrew, who stepped back from royal duties in 2019.
Buckingham Palace said earlier in the day that Elizabeth had been placed under medical supervision because of her health concerns. Senior members of the royal family, including William, Andrew and Elizabeth's third son Edward and his wife, arrived in Scotland to be with the queen. Over the past year, 96-year-old Elizabeth had health issues.
The British government no longer has a political or executive role for the head of state. Buckingham Palace says that kings and queens work year-round with support from their family. Over the last few years, Charles has taken over some of his mother's duties. Earlier this year, Elizabeth indicated she would like Charles' second wife to become queen consort instead of princess consort, a move widely seen as Elizabeth's endorsement of the couple after their many rocky years in the public eye.
Queen Elizabeth was the longest-reigning monarch in the United Kingdom.
Queen Elizabeth says she would like to see her grandson become a queen.
There are plans for Queen Elizabeth's death and funeral.
Mobility issues are what we know about the queen's health in recent months.
The doctors are concerned for her health.