Elizabeth II ascended the throne because the former King George VI had no son, so his daughter had to inherit the throne and become the queen. Elizabeth today will not succeed to the throne. Her father's brother Edward VIII fell in love with a divorced American woman, Mrs Simpson, and gave up the throne for her. But Edward VIII had no children and could only be inherited by his younger brother George. George VI is Elizabeth's father. He has no son. So now the king of England is the queen.
In the history of Europe, regardless of the chivalry system in ancient Greece, ancient Rome or the Middle Ages, titles such as "emperor" and "king" have always been the patents of men, and women acceded to the throne as monarchs because after the death of the king's husband, when the heir was still young or there was no suitable heir, the queen was in charge of power, and then she was honored as the throne. The Queen of England is lady sovereign of England. The British monarch is the head of state of Britain and its overseas territories. Now the male monarch is called the king, and lady sovereign is called the queen.
From the14th century, in one country after another, one queen (emperor) appeared intermittently, until now, a total of 30. There are 6 Britons, 4 Russians, 3 Dutch, 2 Luxemburg, 3 Spaniards, 2 Portuguese, 2 Swedes, 2 Danes, 1 Austrian, 1 Polish, 1 Hungarian, and merged countries, such as Scotland, Navarra, Naples.