Here is the ranking of the world's 25 richest people as estimated by Forbes magazine. Listings include rank, name, home country or state, age where known, wealth in billions of dollars and source of the money.

Forbes says the research that when into compiling the rankings began in early 2006 and ended on Feb. 9, 2007.

1. William Gates III, Washington, 51, $56, Microsoft
2. Warren Buffett, Nebraska, 76, $52, Berkshire Hathaway
3. Carlos Slim Helu, Mexico, 67, $49, telecom
4. Ingvar Kamprad and family, Sweden, 80, $33, Ikea
5. Lakshmi Mittal, India, 56, $32, steel
6. Sheldon Adelson, Nevada, 73, $26.5, casinos, hotels
7. Bernard Arnault, France, 58, $26, LVMH
8. Amancio Ortega, Spain, 71, $24, Zara
9. Li Ka-shing, Hong Kong, 78, $23, diversified
10. David Thomson and family, Canada, 49, $22, inheritance
11. Lawrence Ellison, California, 62, $21.5, Oracle
12. Liliane Bettencourt, France, 84, $20.7, L'Oreal
13. Prince Alwaleed Bin Talal Alsaud, Saudi Arabia, 50, $20.3, investments
14. Mukesh Ambani, India, 49, $20.1, petrochemicals
15. Karl Albrecht, Germany, 87, $20, Aldi
16. Roman Abramovich, Russia, 40, $18.7, oil
17. Stefan Persson, Sweden, 59, $18.4, Hennes & Mauritz
18. Anil Ambani, India, 47, $18.2, diversified
19. Paul Allen, Washington, 54, $18, Microsoft, investments
20. Theo Albrecht, Germany, 84, $17.5, Aldi, Trader Joe's
21. Azim Premji, India, 61, $17.1, software
22. Lee Shau Kee, Hong Kong, 79, $17, real estate
23. Jim Walton, Arkansas, 59, $16.8, Wal-Mart
24. Christy Walton and family, Wyoming, 52, $16.7, Wal-Mart inheritance
24. S. Robson Walton, Arkansas, 63, $16.7, Wal-Mart