RICHEST PEOPLE IN THE WORLD.

Bill Gates is back on top after a four-year hiatus, reclaiming the title of world’s richest person from telecom mogul Carlos Slim Helu of Mexico, who ranked No. 1 for the past four years. Gates, whose fortune rose by $9 billion in the past year, has held the top spot for 15 of the past 20 years. Spanish clothing retailer Amancio Ortega (best known for the Zara fashion chain) retains the No. 3 spot for the second year in a row, extending his lead over Warren Buffett, who is again No. 4. American gambling
tycoon Sheldon Adelson, who added $11.5 billion to his pile, makes it back into the top ten for the first time since 2007. Another first: A record net worth of $31 billion was needed to make the top 20, up from $23 billion last year.

The year’s biggest dollar gainer was Facebook’s Mark Zuckerberg, whose fortune jumped $15.2 billion, to $28.5 billion, as shares of his social network soared. Tech, and more specifically Facebook, helped propel numerous fortunes lately. The company’s COO,Sheryl Sandberg, joins the ranks for the first time, as does Facebook’s longtime vice president Jeff Rothschild. Also, thanks to a $19 billion deal  (including restricted stock) with Facebook, WhatsApp founders Jan Koum and Brian Acton join the ranks of Silicon Valley’s wealthiest for the first time. They are 4 of 26 newcomers whose fortunes come from technology, 10 of whom are American, including Dropbox CEO Drew Houston and Workday cofounder Aneel Bhusri.

Thanks to the tech boom, and strong stock market, the U.S. once again leads the world with 492 billionaires, followed by China with 152 and Russia with 111. But wealth is spreading to new places. We found billionaires for the first time in Algeria, Lithuania, Tanzania and Uganda. Also for the first time, an African,Aliko Dangote of Nigeria, breaks into the top 25. Worth $25 billion, he moves up 20 spots.