The Electress Sophia of Hanover was born Sophia, Pfalzgräfin von Simmern, at The Hague on October 14, 1630, and died at Herrenhausen on June 8, 1714. Daughter of Frederick V, Elector Palatine also known as King Frederick V of Bohemia and Elizabeth Stuart also known as Queen Elizabeth of Bohemia.
She married Ernst August, Duke of Brunswick-Lüneburg at Heidelberg September 30, 1658. He became the Elector of Hanover in 1692. (Electors were princes who had the right to vote to elect the emperor of the Holy Roman Empire.)
As the daughter of Elizabeth Stuart, in turn the daughter of James I & VI of England and Scotland, she was inserted into the line of succession to the British throne behind Queen Anne, as her closest Protestant heir, by the Act of Settlement of 1701, for the purpose of cutting off any claim by the Catholic James Francis Edward Stuart, who would otherwise have become King James III.
Sophia would have inherited the throne if she had not died before Anne. Upon her death, Sophia's son Elector Georg Ludwig of Hanover became heir-presumptive, and weeks later succeeded Queen Anne as King George I of Great Britain.
The Act of Settlement restricts the throne to the "Protestant heirs" of Sophia of Hanover who have never been Catholic and who have never married a Catholic. The Royal Marriages Act of 1772 also provides that, with certain exceptions, they must apply for permission from the British monarch for any marriage they make. Presently there are almost 5000 descendants of Sophia although not all are in the line of succession. The Sophia Naturalization Act of 1705 granted the right of British citizenship to Sophia's non-Catholic descendants (though this has been modified by subsequent laws).
Before her marriage, Sophia, as the daughter of Frederick V, Elector Palatine of the Rhine, was referred to as Sophie, Princess Palatine of the Rhine, or as Sophia of the Palatinate.