Bill Gates and Warren Buffett answering questions from business students at the University of Nebraska

Forbes' annual list of the world's dollar billionaires has named Warren Buffett the richest person on the planet, surpassing his friend Bill Gates, who had held the title for 13 consecutive years.

America's best known investor who has willed most of his fortune to the Bill and Melinda Gates Foundation, is worth an estimated $62 billion, up $10 billion from a year ago because of the jump in the value of Berkshire Hathaway stock.

Bill Gates, Microsoft Chairman and co-Founder, is now ranked as the world's third richest person. At $58 billion, his net worth is up $2 billion from a year ago. Mexican telecom tycoon Carlos Slim Helu was named the world's second richest man, with a net worth of around $60 billion, up $11 billion since last March. India's steel magnate Lakshmi Mittal is in fourth place.

Forbes' rich list has named more than 1,000 billionaires from around the world, with 226 newcomers. The total net worth of the group is $4.4 trillion, up $900 billion from 2007.

This year's list has has a growing number from emerging markets, such as China, India and Russia.

In 2006, 10 of the top 20 billionaires were from the United States. This year, there are only four. Four of the 10 richest in the world are from India, the highest number for a single country.

The US has the most billionaires with 42 percent of the total and 37 percent of the total wealth, according to Forbes.

Russia has 87 billionaires and is in second place behind the US; Germany has 59 billionaires, which held that position for six years. Ireland has four who were born in Ireland.

The rankings include 226 newcomers. Seventy-seven of the new faces come from the U.S., half of whom made their fortunes in finance and investments, including John Paulson and Philip Falcone, both of whom became wealthy shorting subprime debt. Another third of the new billionaires comes from Russia (35), China (28) and India (19). Two of the most noteworthy new entrants are South Africa's Patrice Motsepe and Nigeria's Aliko Dangote, the first black Africans to make their debut among the world's richest. Dangote is also the first-ever Nigerian billionaire.

It is also a record-breaking year for young billionaires, with Forbes finding 50 under the age of 40, 25 of whom are new to the list. Sixty-eight percent of these under-age-40 tycoons built their 10-figure fortunes from scratch, including Google co-founders Sergey Brin and Larry Page; former Enron trader John Arnold, who now runs a hedge fund; India's Sameer Gehlaut, who started online brokerage Indiabulls; and, last but not least, Facebook founder Mark Zuckerberg, who at age 23 might just be the youngest self-made billionaire in history.

Zuckerberg is probably destined to be the most talked about newcomer of the year because of his age and ingenious social-networking site, but there are fascinating entrepreneurs of all ages climbing into the ranks. Some of the more notable ones include China's Gao Dekang, who is one of the world's biggest makers of down jackets and vests; Portugal's Americo Amorim, who turned his grandfather's small cork operation into the world's largest; and Brazil's Eike Batista, who built and lost a gold mining fortune, before hitting it big in iron ore. He is now one of the world's richest mining billionaires.