<human>:  Tell me about the history of the British monarchy
<bot>: The British monarchy has a long and distinguished history and has played a significant role in shaping the United Kingdom since its formation in the 10th century. The kingdom was formed when King Athelstan unified the Anglo-Saxon kingdoms of England, creating the first monarch in the form of a royal family. Over the subsequent centuries, this royal family has evolved, often undergoing dramatic changes as the kingdom grew. From the 12th century onward, the monarchy shifted towards a more centralized form of government and power, eventually becoming a parliamentary monarchy in the 17th century. During this time, the monarchy acquired much more political power, including the role of choosing the Prime Minister. This institution has stayed largely the same throughout the 20th century, with the current monarch, Queen Elizabeth II, reigning since 1952.