Britain's Prince William and his girlfriend Kate Middleton are to get married on Friday.
William is second in line to the throne after his father, Prince Charles. Here are some details about the succession to the British throne:
* SOME FACTS ABOUT SUCCESSION:
-- The succession to the throne is regulated not only through descent, but also by parliamentary statute. The order of succession is the sequence of members of the royal family in the order in which they stand in line to the throne.
-- The basis for the succession was determined in constitutional developments which culminated in the Bill of Rights (1689) and the Act of Settlement (1701).
-- Parliament, under the Bill of Rights and the Act of Settlement, also laid down various conditions which the Sovereign must meet.
-- A Roman Catholic is specifically excluded from succession to the throne; nor may the Sovereign marry a Roman Catholic - royal family members who marry a Catholic must give up their right to the throne.
-- The Sovereign must, in addition, be in communion with the Church of England and must swear to preserve the established Church of England and the established Church of Scotland. The Sovereign must also promise to uphold the Protestant succession.
* FAMILY:
-- The Queen decides which members of her family are accorded the status of members of the royal family and also, from time to time, approves their precedence in the line of succession.
-- The Queen determines both separate precedence (for ladies and gentlemen) and also joint precedence.
-- The children, grandchildren and great-grandchildren of a sovereign, as well as their spouses, are members of the royal family. First cousins of the monarch may also be included. Children are included on coming of age or after they have completed their education.
* THE LINE OF SUCCESSION - THE TOP 20:
1. The Prince of Wales
2. Prince William of Wales
3. Prince Harry
4. The Duke of York
5. Princess Beatrice of York
6. Princess Eugenie of York
7. The Earl of Wessex
8. Viscount Severn
9. The Lady Louise Mountbatten-Windsor
10. The Princess Royal
11. Mr. Peter Phillips
12. Miss Zara Phillips
13. Viscount Linley
14. The Hon. Charles Armstrong-Jones
15. The Hon. Margarita Armstrong-Jones
16. The Lady Sarah Chatto
17. Master Samuel Chatto
18. Master Arthur Chatto
19. The Duke of Gloucester
20. Earl of Ulster
Sources: Reuters/www.royal.gov.uk