Today, Queen Elizabeth II becomes the longest-reigning British monarch in history, and the longest reigning woman monarch of any nation. Queen Victoria reigned from June 20, 1837 until her death on January 22, 1901. That was 63 years and 216 days.
Victoria’s great-great-granddaughter Queen Elizabeth ascended the throne upon the death of her father on February 6, 1952. That was also 63 years and 216 days ago. Sometime today (the time difference is confusing), Elizabeth eclipses that length.
At her birth in 1926, Elizabeth was not expected to ascend to the throne, despite being third in line. It was assumed for some time that her uncle, King Edward VIII, would eventually produce an heir. He abdicated in 1936, making his younger brother George VI the royal monarch. George's oldest daughter, 10-year-old Elizabeth, then became the next in the line of royal succession. Even then, it was possible for her parents to have birthed a son, who would have skipped ahead of Elizabeth in line. But that didn't happen.
Elizabeth married Prince Philip of Greece and Denmark in 1947. He is her second cousin once removed on one side and third cousin on another side. They have been married almost 67 years.
Elizabeth and Philip have four children, eight grandchildren, and five great-grandchildren. You can see the line of royal succession here.
Elizabeth is actually the second-longest reigning monarch alive, after Rama IX of Thailand, who has been king since June of 1946. And there have been a couple of monarchs who ruled for over 80 years. However, they were both infants when they ascended the throne. Elizabeth is certainly an outlier.
So as of today….