No.1 Bill Gates
$53 billion
Microsoft, U.S.
Software visionary is now the world's second-richest man. Net worth still up $13 billion in a year as Microsoft shares rose 50% in 12 months, value of investment vehicle Cascade swelled. More than 60% of fortune held outside Microsoft; investments include Four Seasons hotels, Televisa, Auto Nation. Stepped down from day-to-day duties at Microsoft in 2008 to focus on philanthropy.
No.2 Lawrence Ellison 
$28 billion - Oracle, U.S.
Oracle founder's fortune continues to soar; shares up 70% in past 12 months. Database giant has bought 57 companies in the past five years. Completed $7.4 billion buyout of Sun Microsystems in January; acquired BEA Systems for $8.5 billion in 2008. Studied physics at U. of Chicago; didn't graduate. Started Oracle 1977; took public a day before Microsoft in 1986.
No.3 Sergey Brin
Net worth: $17.5 billion
The Google cofounder's hot streak brings him up a couple of rankings to 24th richest in the world. His fortune grew $5.5 billion as shares of the search giant rose 70% in past year. Google revenues hit $23.7 billion. Unveiled smart phone Nexus One in January; operates with Android software. Announced upgraded version of Chrome browser in March. Emigrated from Russia, met future partner Larry Page at Stanford; duo dropped out of computer science Ph.D. program in 1998. Brin introduced goats to Google's campus last year, since animals are less harmful to the environment than lawn mowers.
No.4 Larry Page
Net worth: $17.5 billion
The surge in Google stock pushed up cofounder Page's fortune by $5.5 billion and lands him as 24th richest. Google continues to dominate search, though it has seen Microsoft's Bing search engine--launched in 2009--take a slice of its market share. The company has moved into mobile phones and mobile software with the January launch of its Nexus One smart phone, which uses its Android operating system software. Google Apps--including Google Docs and Google Calendar--are a $750 million piece of the overall business and growing. Page met Brin at Stanford, where the pair founded Google.
No.5 Azim Premji
Net worth: $17 billion
Software czar's net worth jumped more than $11 billion in the past year, while his ranking among billionaires went from 83rd to 28th this year. Premji chairs Wipro, India's third-largest software exporter, which reported net profits in the last two quarters, signaling a rebound for the U.S.-dependent outsourcing giant. The Azim Premji Foundation, his charitable arm, plans to set up Azim Premji University. He co-chaired the World Economic Forum's annual meeting in Davos this year. Eldest son Rishad, a Harvard grad, is Wipro's general manager for treasury and investor relations.
No.6 Steve Ballmer
Net worth: $14.5 billion
Ballmer's net worth increased $3.5 billion in the last year, as Microsoft's shares climbed 50%. In 2009 the manic Microsoft chief finally cut a deal with Yahoo (after failed acquisition attempts) to pay for its search technology. The company's new operating system Windows 7, released in October 2009, was hailed as much better than predecessor Vista. The upcoming Windows Phone 7 Series mobile operating system surprised and delighted pundits. Ballmer, famous for impassioned stage antics, pretended to stomp on an iPhone at a company event last year, after an employee snapped a picture with Apple's offending device.
No.7 Bernard Arnault
$27.5 billion
Luxury goods, France.
Bling is back, helping fashion icon grab title of richest European as shares of his luxury goods outfit LVMH--maker of Louis Vuitton, Moet & Chandon--surge 57%. LVMH is developing upscale Shanghai commercial property, L'Avenue Shanghai, with Macau billionaire Stanley Ho.
No.8 Paul Allen
Net worth: $13.5 billion
Microsoft cofounder's net worth rose $3 billion in the last year. Allen, who left Microsoft long ago, recently launched software outfit Xiant, whose product Filer helps users keep track of emails in Microsoft's Outlook. Though he no longer chairs Charter Communications, which recently emerged from bankruptcy, Allen still controls 35% of voting interest in the cable outfit. The philanthropist has been diagnosed with lymphoma and is undergoing chemotherapy treatment.
No.9 Michael Dell
Net worth: $13.5 billion
Dell's net worth rose $1.2 billion from a year ago, but his ranking among dropped to 37th from 25th last year. The leader of one of the world's largest PC-makers, trying to claw its way back to the top, completed a purchase of IT services outfit Perot Systems in November 2009. Dell returned to the company helm two years ago, brought new management, restructured divisions. Dell introduced smart phone and tablet devices in the past few months. The company's stock slipped nearly 10% in the past six months, however, and revenue fell 13% in the year ended January 2010.
No.10 Jeffrey Bezos
Net worth: $12.3 billion
Bezos' fortune rose $5.5 billion in the past year, as Amazon shares climbed 100%. His rank on the billionaires list is 43rd this year, up from 68th last year. Bezos launched the Kindle digital book reader in 2007; Kindle 2 debuted in 2008. Amazon's net income increased 40% while the economy crashed in 2009, as bargain-hunters flocked to its online marketplace for low prices and convenience. It also acquired online shoe retailer Zappos in July 2009 for $800 million in stock.
