Did you know that Britain’s royal family traces its ancestry back nearly 1,000 years? It dates all the way to William the Conqueror in 1066, and the monarchy has certainly evolved since then!

So with such a long family history, how is it decided who gets to serve as the next king or queen? The decision of who inherits the British throne is determined by the line of succession. Starting with William the Conqueror, the monarchy passed from the king to his firstborn son. This continued for hundreds of years until the British Parliament passed an act in 1702 allowing a woman to inherit the throne—but only as long as there wasn’t a male heir available to take her place.

That rule lasted for three hundred years until Parliament updated the law again in 2013. The throne is now allowed to pass to the first-born heir, regardless of whether the monarch had a son or daughter first.

In the history of the monarchy, there have only been six women to ascend to the British throne. Queen Victoria, a famous monarch who shaped her country, served for 63 years from 1837 to 1901. Queen Elizabeth II, who was Victoria’s great-great-granddaughter, served for 70 years!

England has a long and complicated history in the world. Throughout that history, the monarchy grew to include not just England, but Great Britain as well. Additionally, King Charles III, the newest monarch after his mother’s death last month, is head of the Commonwealth, an association of 56 independent countries. For 14 of those countries, he is also head of state.

King Charles has two sons, Prince William and Prince Harry. With his grandmother’s passing, Prince William is now heir to the throne. Prince William’s first-born child is Prince George, and he is now second in line to the throne. Under the updated rules of succession, if Prince George one day has a daughter as his first child, she would be heir to the throne!